1. A current carrying coil is subjected to a uniform magnetic field. The coil will orient so that its
plane becomes    ?
(a) inclined at 45° to the magnetic field
(b) inclined at any arbitrary angle to the
magnetic field
(c)   parallel to the magnetic field
(d)   perpendicular to magnetic field
Ans:c
2. Tesla is the unit of
(a)    magnetic flux
(b)    magnetic field
(c)    magnetic induction
(d)    magnetic moment
Ans:b
3. Energy in a current carrying coil is stored in the
form of   ?
(a) electric field
(b) magnetic field
(c) dielectric strength
(d) heat
Ans:b
4. The total charge induced in a conducting loop when it is moved in magnetic field depends on?
(a) the rate of change of magnetic flux
(b) initial magnetic flux only
(c) the total change in magnetic flux
(d) final magnetic flux only.
Ans:c
5. The magnetic induction at a point P which is at the distance of 4 cm from a long current carrying
wire is 10
 
-3
 T. The field of induction at a distance 12 cm from the current will be ?
(a) 3.33 x 10
-4
 T
(b) 1.11x 10
-4
 T
(c) 3×10
-3
 T
(d) 9×10
Ans:a
-3
 T
6. A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in
negative X-direction. As a result, the charge will
(a) remain unaffected
(b) start moving in a circular path in Y—Z plane
(c) retard along X-axis
(d) moving along a helical path around X-axis
Ans:a
7. A uniform magnetic field acts right angles to the direction of motion of electrons. As a result, the
electron moves in a circular path of radius 2cm. If the speed of electrons is doubled, then the radius
of the circular path will be ?
(a)2.0 cm
(b) 0.5 cm
(c)4.0cm
(d) 1.0cm
Ans:c
8. A deuteron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 metre in a plane
perpendicular to magnetic field B. The kinetic energy of the proton that describes a circular orbit of
radius 0.5 metre in the same plane with
the same B is
(a)25 keV
(b) 50 keV
(c)200 keV
(d) 100 keV
Ans:d
9. A straight wire of length 0.5 metre and carrying a current of 1.2 ampere is placed in uniform
magnetic field of induction 2 Tesla. The magnetic field is perpendicular to the length of the wire. The
force on the wire is ?
(a) 2.4N
(b) 1.2N
(c) 3.0 N
(d) 2.0 N
Ans:b
10. To convert a galvanometer into an ammeter, one needs to connect a ?
(a) low resistance in parallel
(b) high resistance in parallel
(c) low resistance in series
(d) high resistance in series.
Ans:a
11. A coil carrying electric current is placed in uniform magnetic field
(a) torque is formed
(B) e.m.f is induced
(c) both (a) and (b) are correct
(d) none of the above
Ans:a
12. The magnetic field at a distance ‘r’ from a long wire carrying current ‘i’ is 0.4 Tesla. The magnetic
field at a distance ‘2r’ is ?
(a)0.2Tesla
(b) 0.8 Tesla
(c)0.1 Tesla
(d) 1.6 Tesla
Ans:a
13. A electron enters a region where magnetic (B) and electric (E) fields are mutually
perpendicular, then ?
(a) it will always move in the direction of B
(b) it will always move in the direction of E
(c) it always possesses circular motion
(d) it can go un deflected also.
Ans:d
14. A straight wire of diameter 0.5 mm carrying a current of 1 A is replaced by another wire of I mm
diameter carrying same current. The strength of magnetic field far away is?
(a) twice the earlier value
(b) same as the earlier value
(c) one-half of the earlier value
(d) one-quarter of the earlier value
 
Ans:b
15. At what distance from a long straight wire carrying a current of 12 A will the magnetic field
be equal to 3×10
 
-6
 Wb/metre Square
(a) 8×10
-2
 m
(b) 12×10
-2
 m
(c)18x 10
-2
 m
(d) 24×10
Ans:a
-2
 m
16. An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field B at the
centre of the circle. The radius of the circle is proportional to ?
(a) √(B/v)
(b) B/v
(c) √(v/B)
(d)v/B
Ans:d
17. A 10 eV electron is circulating in a plane at right angles to a uniform field at magnetic induction
10
-4
 Wb/m
2
 (= 1.0 gauss). The orbital radius of the electron is ?
(a) 12cm
(b) 16cm
(c) 11cm
(d) 18cm
Ans:c
18. A galvanometer acting as a voltmeter will have?
(a) a low resistance in series with its coil.
(b) a high resistance in parallel with its coil
(c) a high resistance in series with its coil
(d) a low resistance in parallel with its coil
Ans:c
19. A beam of electrons is moving with constant velocity in a region having simultaneous
perpendicular electric and magnetic fields of strength 20 Vm
-1
 and 0.5 T respectively at right angles
to the direction of motion of the electrons. Then the velocity of electrons must be?
(a) 8m/s
(b) 20 m/s
(c) 40m/s
(d) 1/40 m/s
Ans:c
20. A galvanometer of resistance 20 Ohms gives full scale deflection with a current of 0.004 A. To
convert it into an ammeter of range 1 A, the required shunt resistance should be?
(a) 0.38 Ohms
(b) 0.21 Ohms
(c) 0.08 Ohms
(d) 0.05 Ohms
Ans:c
21. A long solenoid carrying a current produces a magnetic field B along its axis. If the current is
doubled and the number of turns per cm is halved, the new value of the magnetic field is ?
(a) 4B
(b) B/2
(c) B
(d) 2B
Ans:c
22. A positively charged particle moving due east enters a region of uniform magnetic field directed
vertically upwards. The particle will
(a) continue to move due east
(b) move in a circular orbit with its speed unchanged
(c) move in a circular orbit with its speed increased
(d) gets deflected vertically upwards.
Ans:b
23. Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current
The force of attraction per unit length between the two wires is?
(a)2 x10
 
-7
 N/m
(b) 2 x10
-8
 N/m
(c) 5×10
-8
 N/m
(d)10
Ans:a
-7
 N/m
24. A galvanometer having a resistance of 8 ohms is shunted by a wire of resistance 2 ohms. If the
total current is 1 amp, the part of it passing through the shunt will be?
(a)0.25 amp
(b) 0.8 amp
(c)0.2 amp
(d) 0.5 amp
Ans:b
25. A coil of one turn is made of a wire of certain length and then from the same length a coil of two
turns is made. If the same current is passed in both the cases, then the ratio of the magnetic
inductions at their centres will be?
(a)2:1
(b)1:4
(c)4:1
(d)1:2
Ans:b
26. Magnetic field intensity in the centre of coil of 50 turns, radius 0.5 m and carrying a current of
2A is ?
(a) 0.5 x 10
-5
 T
(b) 1.25x 10
(c) 3x 10
(c) 4 x 10
Ans:b
-5
-4
 T
-5
 T
 T
27. When a proton is accelerated through I V, then its kinetic energy will be?
(a)1840 eV
(b) 13.6eV
(c)1 eV
(d) 0.54eV
Ans:c
28. If a long hollow copper pipe carries a current,thin magnetic field is produced
(a)inside the pipe only
(b)outside the pipe only
(c)both inside and outside the pipe
(d) no where
Ans:b
29. A charged particle moves through a magnetic field in a direction perpendicular to it. Then the
(a) velocity remains unchanged
(b) speed of the particle remains unchanged
(c) direction of the particle remains unchanged
(d) acceleration remains unchanged
Ans:b
30. Two long parallel wires P and Q are both perpendicular to the plane of the paper with distance of
5 m between them. If P and Q carry current of 2.5 amp and 5 amp respectively in the same direction,
then the magnetic field at a point half-way between the wires is ?
(a)3µ/2∏
(b)µ/∏
(c)√3µ/2∏
(d)µ/2∏
Ans:a
31. A proton moving with a velocity 3 x 10
 
5
 m/s enters a magnetic field of 0.3 Tesla at an angle of
30° with the field. The radius of curvature of its path will be (e/m for proton – 10
 C/kg)
(a)2cm
(b) 0.5 cm
(c)0.02 cm
(d) 1.25 cm
Ans:b
32. A charged particle of charge q and mass m enters perpendicularly in a magnetic field B. Kinetic
energy of the particle is E; then frequency of rotation is?
(a)qB/m∏
(b) qB/2m∏
(c)qBE/2m∏
(d) qB/2E∏
Ans:b
33. A galvanometer can be converted into a voltmeter by connecting?
(a) A high resistance in parallel
(b) A low resistance in series
(c) A high resistance in series
(d) A low resistance in parallel
Ans:c
34. A wire carries a current. Maintaining the same current it is bent first to form a circular plane coil
of one turn which produces a magnetic field B at the centre of the coil. The same length is now bent
more sharply to give a double loop of smaller radius. The magnetic field at the centre of the double
loop, caused by the same current is ?
(a)4B
(b) B /4
(c) B/2
(d) 2B
Ans:a
8
35.A bar magnet is oscillating in earth’s magnetic field with a period T. What happens to its period of
motion, if its mass is quadruped ?
(a) Motion remains simple harmonic with new period =T/2
(b) Motion remains simple harmonic with new period = 2 T
(c) Motion remains simple harmonic with new period =4T
(d) Motion remains simple harmonic and the period stays nearly constant
Ans:b
36. The work done in turning a magnet of magnetic moment M by an angle of 90° from the meridian,
is n times the corresponding work done to turn it through an angle of 60°.
The value of n is given by
(a)2
(b) 1
(c) 0.5
(d) 0.25
Ans:a
37 . For protecting a sensitive equipment from the external electric arc, it should be ?
(a) Wrapped with insulation around it when passing current through it
(b) Placed inside an iron can
(c) Surrounded with fine copper sheet
(d) Placed inside an aluminium can
Ans:b
38. If a diamagnetic substance is brought near north or south pole of a bar magnet, it is?
(a) attracted by the poles
(b) repelled by the poles
(c) repelled by north pole and attracted by the south pole
(d) attracted by the north pole and repelled by the south pole
Ans:b
39. Current i is flowing in a coil of area A and number of turns N, then magnetic moment of
the coil is M= ?
(a) NiA
(b) Ni/A
(c)Ni/√A
(d) N
Ans:a
 
2
Ai
40. Two magnets of magnetic moments M and 2M are placed in a vibration magnetometer, with the
identical poles in the same direction. The time period of vibration is T
. If the magnets are placed
with opposite poles together and vibrate with time period T
 then ?
(a) T
 is infinite
(b) T
2
2
=T

(c)T
2
>T

(d) T
2
1
1
 is less than T
1
 
2
Ans:c
41. A diamagnetic material in a magnetic field moves
(a) perpendicular to the field
(b) from stronger to the weaker pans of the field
(c) from weaker to the stronger parts of the field
(d) in none of the above directions
Ans:b
42. According to Curie’s law, the magnetic susceptibility of a substance at an absolute
temperature T is proportional to?
1
(a) T
 
2

(b) 1/T
(c) T
(d) 1/T
Ans:b

1. General gas equation is
(a) PV = RT
(b) PV= mRT
(c) PV = Constant
(d) = constant
ANSWER: (a)
2. An isolated system is one, which
(a) Permits the passage of energy and matter
across the boundaries
(b) Permits the passage of energy only
(c) Does not permit the passage of energy and matter across it
(d) Permits the passage of matter only
ANSWER: (b)
3. In an isolated system, boundary of the system is
crossed by
(a) Heat
(b) Work
(c) Mass
(d) Both (a) and (b) above
ANSWER: (d)
4. The characteristic of a control volume is/are
(a) The volume, shape and position with respect to an observer are fixed
(b) Material flow across the boundary
(c) Both (a) and (b) above
(d) None of the above
ANSWER: (c)
5. Specific heat is the amount of heat required to raise the temperature
(a) By unit degree of a substance
(b) By unit degree of a unit mass
(c) Of a unit mass by 10°
(d) None of the above
ANSWER: (b)
6. Internal energy of a perfect gas depends upon
(a) Temperature only
(b) Temperature and pressure
(c) Temperature, pressure and specific heats
(a) None of the above
ANSWER: (a)
7. With rise of temperature, the specific heat of
water
(a) Increases
(b) Decreases
 
(c) First decreases to minimum then increases
(d) Remains constant
ANSWER: (c)
8. For a closed system, difference between the heat added to the system and work done by the gas,
is
equal to the change in
(a) Enthalpy
(b) Entropy
(c) Internal energy
(d) Temperature
ANSWER: (c)
9. Specific heat of water is
(a) 1
(b) 0.1
(c) 0.97
(d) None of the above
ANSWER: (a)
10. Properties of the system, whose value for the entire system is equal to the sum of their values
for individual parts ofthe system, are known as
(a) Thermodynamic properties
(b) Extensive properties
(c) Intensive properties
(d) None of the above
ANSWER: (b)
1. The extensive property of a thermodynamic system is
(a) Viscosity
(b) Surface tension
(c) Refractive index
(d) Heat capacity
ANSWER: (d)
12. Thermal equilibrium between two or more bodies exists, when they are brought together; there is
no change in
(a) Density
(b) Pressure
(c) Temperature
(d) All of the above
ANSWER: (c)
13. When two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium
with each other This statement is
(a) Zero the law of thermodynamics
(b) First law of thermodynamics
(c) Second law of thermodynamics
(d) None of the above
ANSWER: (a)
14. First law of thermodynamics deals with conservation of
(a) Mass
(b) Heat
(c) Momentum
(d) Energy
ANSWER: (d)
 
15. According to first law of thermodynamics
(a) total energy of a system remains constant
(b) total energy of a system during a process
remains constant
(c) enthalpy entropy and total energy remains constant
(d) none of the above
ANSWER: (a)
16. For the measurement of thermodynamic property known as temperature, is based on
(a) Zeroth law of thermodynamics
(b) First law of thermodynamics
(c) Second law of thermodynamics
(b) Third law of thermodynamics
ANSWER: (a)
17. Energy can neither be created nor destroyed but only converted from one form to another. This
statement is
(a) Zeroth law of thermodynamics
(b) First law of thermodynamics
(c) Second law of thermodynamics
(d) None of the above
ANSWER: (b)
18. Kelvin-Plank’s law’ deals with
(a) Conversion of work into heat
(b) Conversion of heat into work
(c) Conservation of work
(d) Conservation of heat
ANSWER: (b)
19. A perpetual motion machine of the first kind is a machine which produces power without
consuming any energy is,
(a) Possible according to first law of thermodynamics
(b) Impossible according to first law of thermodynamics
(c) Impossible according to second law of thermodynamics
(d) Possible according to second law of thermodynamics
ANSWER: (b)
20. Heat flows from cold substance to hot substance with the aid of external work This statement is
given by
(a) Kelvin
(b) Joule
(c) Gay Lussac
(d) Clausius
ANSWER: (d)
21. The fastest moving gas molecules are of
(a) Oxygen
(b) Hydrogen
(c) Chlorine
(d) Nitrogen
ANSWER: (b)
22. In actual gases, the molecular collisions are
(a) Elastic
(b) Plastic
(c) Inplastic
(d) Ineclastic
ANSWER: (d)
 
23. If a perfect gas, undergoing any change in the variable, which control physical properties, it’s
behaviour is governed by
(a) Boyle’s law
(b) Charles’s law
(c) Gay Lussac law
(d) All of the above
ANSWER: (d)
24. According of Boyle’s law at constant temperature PV= C. In this relation value of C
depends upon
(a) Atmospheric pressure
(b) Quantity Of the gas
(c) Molecular weight of the gas
(d) All of the above
ANSWER: (b)
25. Change of internal energy is proportional to the change of temperature. This is
(a) Boyle’s law
(b) Charles’s law
(c) Joule’s law
(d) Gay Lussac law
ANSWER: (c)
...............................................--------------------------------..................................................

Solved Objective MCQ test on Fluid mechanics
1. In Red wood viscometer
(a) Absolute value of viscosity is detemiined
(b) Part of the head of fluid is utilized in
Overcoming friction
(c) Fluid discharges through orifice with
negligible velocity
(d) Comparison of viscosity is done.
ANSWER: (d)
2. Centre of buoyancy is
(a) The point of intersection of buoyant force and
centre line of the body
(b) Centre of gravity of the body
(c) Centric of displaced volume fluid
(d) Midpoint between C.G. and metacentric.
ANSWER: (c)
3. In isentropic flow; the temperature
(a) Cannot exceed the reservoir temperature
(b) Cannot drop and again increase downstream
(c) Is independent of Match number
(d) Is a function of Match number only
ANSWER: (a)
4. A stream line is
(a) The line of equal velocity in a flow
(b) The line along which the rate of pressure drop
is uniform
(c) The line along the geometrical centre of the
flow
(d) Fixed in space in steady flow.
ANSWER: (d)
 
5. The flow of water in a pure of diameter 3000
mm can be measured by
(a) Venturimeter
(b) Rotameter
(c) Pilot tube
(d) Orifice plate.
ANSWER: (c)
6. Apparent shear forces
(a) Can never occur in frictionless fluid
regardless of its motion
(b) Can never occur when the fluid is at rest
(c) Depend upon cohesive forces
(d) All of the above
ANSWER: (d)
7. Weber number is the ratio of
(a) Inertial forces to surface tension
(b) Inertial forces to viscous forces
(c) Elastic forces to pressure forces
(d) Viscous forces to gravity
ANSWER: (a)
8. A small plastic boat loaded with pieces of steel
rods is floating in a bath tub. If the cargo is dumped
into the water allowing the both to float empty, the
water level in the tub will
(a) Rise
(b) Fall
(c) Remains same
(d) Rise and then fall
ANSWER: (b)
9. A flow in which each liquid particle has a
definite path and their paths do not cross each
other, is called
(a) Steady flow
(b) Uniform flow.
(c) Streamline flow
(d) Turbulent flow
ANSWER: (c)
10. Buoyant force is
(a) Resultant of up thrust and gravity forces acting
on the body
(b) Resultant force on the body due to the fluid
surrounding it
(c) Resultant of static weight of body and
dynamic thrust of fluid’
(d) Equal to the volume of liquid displaced by
the body
ANSWER: (d)
11. Cavitations is caused by
(a) High velocity
(b) Low barometric pressure
(c) High pressure
 
(d) Low pressure
ANSWER: (d)
12. The general energy equation is applicable to
(a) Steady flow
(b) Unsteady flow
(c) Non-uniform flow
(d) Turbulent flow
ANSWER: (a)
13. The friction resistance in Pipe is proportional
To Square of V , according to
(a) Froudeaiumber
(b) Reynolds-Weber
(c) Darcy-Reynolds
(d) Weber-Froude
ANSWER: (a)
14. Pitot tube is used to measure the velocity head of
(a) Still fluid
(b) Laminar flow
(c) Turbulent flow
(d) Flowing fluid
ANSWER: (d)
15. In equilibrium condition, fluids are not able to sustain
(a) Shear force
(b) Resistance to viscosity
(c) Surface tension
(d) Geometric similitude
ANSWER: (c)
16. Flow occurring in a pipeline when a valve is
being opened is
(a) Steady
(b) Unsteady
(c) Laminar
(d) Vortex
ANSWER: (b)
17. Total pressure on 1 m x 1 m gate immersed vertically at a depth of 2 m below the free water
surface will be
(a) 1000 kg
(b) 2000 kg
(c) 4000 kg
(d) 8000 kg
ANSWER: (a)
18. A large Reynold number is indication of
(a) Smooth and streamline flow
(b) Laminar flow
(c) Steady flow
(d) Highly turbulent flow
ANSWER: (d)
19. In steady flow of a fluid, the acceleration of any
fluid particle is
(a) Constant
(b) Variable
 
(c) Zero
(d) Never zero
ANSWER: (c)
20. Froude number is significant in
(a) Supersonics, as with projectile and jet propulsion
(b) Full immersion or completely enclosed flow, as with pipes, aircrafts wings, nozzles etc.,
(c) Simultaneous motion through two fluids where there is a surface of discontinuity,
gravity forces
(d) All of the above
ANSWER: (c)
21. The flow in venturiflume takes place at
(a) Atmospheric pressure
(b) Vacuum
(c) High pressure
(d) Any pressure
ANSWER: (a)
22. Two dimensional flow occurs when the
(a) Directional and magnitude of the velocity at all points are identical
(b) Velocity of successive fluid particles, at any point, is same at successive periods of time
(c) Magnitude and direction of velocity, do not change from point to point in the fluid
(d) Fluid particles move in a plane or parallel planes and the streamline patterns are
identical in each plane
ANSWER: (d)
23. A piece of wood having weight 5 kg floats in
water with 60% of its volume under the (liquid.
The specific gravity of wood is
(a) 0.83
(b) 0.6
(c) 0.4
(d) None of the above
ANSWER: (b)
24. In order that the water shall never rise more than
100 cm above the crest for a discharge of 5 cubic
metres per second, the length of weir will be
(a) 1 metre
(b) 2.5 metres
(c) 2.49 metres
(d) 2.51 metres
ANSWER: (c)
25. Separation of flow occurs due to reduction of
pressure gradient to
(a) Zero
(b) Negligibly low value
(c) The extent such that vapour formation starts
(d) None of the above
ANSWER: (c)

​

​

1. Two parallel wires separated by 25 cm carry currents of i1 = 25 A and i2 = 35 A flowing in
opposite directions. The force per unit length acting between them is:
(a) a repulsive force of 7 x 104 N/m
(b) an attractive force of 7 x 10-4N/m
(c) a repulsive force of 35 x 102 N/m
(d) an attractive force of 35 x 102 N/m
Ans. (a)
2. In the case of a series L-C-R circuit, the sharpness of resonance curve is determined by the quality
factor Q given by:
(a) XL
XC
(b) L? at resonance frequency
R
(c) L? at any frequency other than resonance frequency
R
(d) XC = XL
Ans. (b)
3. A device used to measure the magnetic field makes use of Hall effect. In a magnetic field of 200 G,
it gives a Hall voltage of 16 ?V. If with the same current and orientation, it gives a Hall voltage of 24
?V in another field, then its magnitude:
(a) 1600G
(b) 480 G
(c) 300 G
(d) 150 G
Ans.(c)
4. Under space charge conditions with the plate voltage Eb = 100 V and the permanence K = 10-4 (in
SI unit), the plate current in a diode will be:
(a) 10-6 mA
(b) l02mA
(c) 102 mA
(d) l0mA
Ans. (a)
5. For a BJT, the current amplification factor cc = 0.9. This transistor is connected in CE
configuration. When the base current changes by 0.4 mA, the change in collector current will be:
(a) 36 mA
(b) 9 mA
(c) 4 mA
(d) 3.6 mA
Ans. (d)
6. A CE amplifier has voltage gain of 50, an input impedance of 1000 Ohms, and an output
impedance of 200 Ohms. The power gain of the amplifier will be:
(a) 24 dB
(b) 41 dB
(c) 250 dB
(d) 12500 dB
Ans. (c)
7. The input signal given to a CE amplifier having a voltage gain of 150 is Vi = 2cos(15t + 10°). The
corresponding output signal is:
(a) 300cos(15t +190°)
(b) 300cos(15t + 90°)
(c) 75cos(15t+10°)
 
(d) 2cos(15t+190°)
Ans. (a)
8. If in the first Bohr orbit of a hydrogen atom the total energy of the electron is 21.76 x 10-19J, then
its potential energy will be:
(a) -43.52 x 10-19J
(b) -27.76 x 10-19J
(c) -10.88 x 10-19J
(d) -13.60 x 10-19J
Ans. (a)
9. Match List I with List H and select the correct answer using the codes given below the Lists:
List I List II
(Processes) (Description)
A. Isothermal process 1. No heat exchange
B. Isentropic process 2. Constant temperature
C. Isochoric process 3. Constant pressure
D. Isobaric process 4. Constant volume
5. Constant enthalpy
Codes:
A B C D
(a) 2 1 5 4
(b) 3 2 4 5
(c) 2 1 4 3
(d) 1 5 2 3
Ans. (c)
10. A system absorbs 1.5 x 103J of energy as heat and produces 500 J of work. The change in the
internal energy of the system will be:
(a) 50J
(b) 100J
(c) 150J
(d) 1000J
Ans. (d)
11. If a capacitor of 1?F charged to a potential of 300 V is discharged through a resistor kept at room
temperature, then the entropy change of the universe in J/K is equal to:
(a) Zero
(b) 0.4 x 10-4
(c) 1.5 x 10-4
(d) 4.0 x 10-4
Ans. (c)
12. The volume of a certain mass of gas at constant pressure is doubled to its value at 0°C. The
temperature of the gas will be:
(a) 100° C
(b) 173°C
(c) 273° C
(d) 546° C
Ans. (c)
13. The period of oscillations of a galvanometer mirror due to the Brownian motion is 40 s. The
moment of inertia of the galvanometer about its suspensions axis is 8 x 10-12 kg-m2. The root-meansquare
of
maximum
deflection
of
this
mirror
at
a
temperature
of
50°C
is:

(a)
2.7
x 10-4
rad

(b)
2.1
x 10-4
rad

(c)
1.5
x 10-4
rad

 
(d) 0.9 x 10-4 rad
Ans. (c)
14. If a black body radiation in a spherical cavity of volume V satisfies the relation PV? = constant
during a quasistatic isentropic process, then the numerical value of i should be:
(a) 7/5
(b) 5/3
(c) 4/3
(d) 3/2
Ans. (c)
Direction: The following ten items consists of two statements, one labelled the ‘Asserti on A’ and the
other labelled the ‘Reason R’. You are to examine these two statements carefully and decide, if the
‘Assertion A’ and the ‘Reason R’ are individually true and if so, whether the
Reason is a correct explanation of the Assertion. Select your answers to these items using the codes
given below and mark your answer sheet accordingly.
Codes:
(a) Both A and Rare true and R is the correct explanation of A
(b) Both A and R are true but R is not a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
15. Assertion (A): The shape of an automobile is so designed that it resembles the streamline pattern
of the fluid through which it moves,
Reason (R): Only then the resistance offered by the fluid is maximum
Ans. (c)
16. Assertion (A): When two vibrating tuning forks having frequencies 256 Hz and 512 Hz are held
near each other, beats cannot be heard.
Reason (R): The principle of superposition is valid only if the frequencies of the oscillators are nearly
equal.
Ans. (a)
17. Assertion (A): Resonance is a special case of forced vibration in which the natural frequency of
vibration of the body is the same as the impressed frequency and the amplitude of forced vibration is
maximum.
Reason (R): The amplitude of forced vibrations of a body increases with the increase in the frequency
of the externally impressed periodic force.
Ans. (c)
18. Assertion (A): A single lens produces a coloured image of an object illuminated by white light.
Reason (R): The refractive index of the material of lens is different for different wavelength of light.
Ans. (a)
19. Assertion (A): At room temperature water does not sublimate from ice to steam.
Reason (R): The critical point of water is much above the room temperature.
Ans. (a)
20. Assertion (A): It is not possible for a system, unaided by an external agency to transfer heat from
a body at a lower temperature to another at a higher temperature.
Reason (R): It cannot violate the second law of thermodynamics.
Ans. (a)
21. Assertion (A): In the absence of an externally applied electric field, the dipole moment per unit
volume of a polar dielectric material is always zero.
Reason (R): In polar dielectrics each molecule has a permanent dipole moment but these are
randomly oriented in the absence of an externally applied electric field.
Ans. (a)
 
22. Assertion (A): If a heavy nucleus is split into two medium sized ones, each of the new nuclei will
have more binding energy per nucleon than the original nucleus.
Reason (R): Joining two light nuclei together to give a single nucleus of medium size means more
binding energy per nucleon in the new nucleus.
Ans. (c)

​

​

23. Assertion (A): In the process of nuclear fission, the fragments emit two or three neutrons as soon
as they are formed and subsequently emit particles.
Reason (R): As the fragments contain an excess of neutrons over .proton, emission of neutrons and
?-1 particles bring their neutron/proton ratio to stable values.
Ans. (a)
24. Assertion (A): The energy gap between the valence band and conduction band is greater in
silicon than in germanium.
Reason (R): Thermal energy produces fewer minority carriers in silicon than in germanium.
Ans. (a)
25. A damped simple harmonic oscillator of frequency f1 is constantly driven by an external periodic
force of frequency f2. At the steady state, the oscillator frequency will be:
(a) f1
(b) f2
(c) f1 – f2
(d) (f1 + f2)/2
Ans. (b)
........................................................................--------------------------......................................

Physics solved previous Objective questions UPSC
physics solved questions for UPSC IAS
UPSC Exam material Physics objective questions and answers
1. Two charged particles A and B have the same linear momentum but A has twice the charge as on
B. Both move in circular paths of radii rA and rB about a magnetic field. Which one of the following is
the correct value of rA/rB
(a) 2
(b) 0.5
(c) 4
(d) 0.25
Ans. (b)
2. The ground state energy of positronium is:
(a) – 1.2eV
(b) – 3.4 eV
(c) – 6.8eV
(d) – 13.6eV
Ans. (c)
3. The minimum wavelength of continuous X-rays is given by:
(a) eh/Vc
(b) ch/eV
(d) cV/eh
(c) eV/ch
(Where the symbols have their usual significance)
Ans. (b)
4. An X-ray of energy 50 keV strikes an electron initially at rest. The change in wavelength of the Xray
scattered
at
angle
90°is,
approximately:

(Given,
h
=
6.63
x 10-34
J-s,
m =
9.11
x 10-31
kg)

(a)
Zero

(b)
2.4x
10-12
m

 
(c) 4.8 x 10-12 m
(d) 2.7 x 10-11 m
Ans. (b)
5. The relationship between the angular frequency —? and the wave number—k (using de-Brolie’s
hypothesis) of a particle associated with it is ? = ck2 , where c is constant. The group velocity for the
particle wave is:
(a) 1/2ck
(b) 1 ck
(c) 2 ck
(d) 4 ck
Ans. (c)
6. A radioactive sample containing No nuclei emits N particles per second on decaying. The half-life of
the sample, in seconds is:
(a) 0.693 (N/No)
(b) (N/No)
(c) 0.693 (No/N)
(d) (No/N)
Ans. (c)
7. For which of the following cases is the de-Broglie wavelength same?
1. Particle of mass m, kinetic energy K
2. Particle of mass 2m, kinetic energy 2K
3. Particle of mass 2m, kinetic energy
Select the correct answer using the codes given below:
(a) 2 and 3
(b) 1 and 3
(c) 1 and 2
(d) 1, 2 and 3
Ans. (d)
8. If E0 is the zero-point energy of a harmonic oscillator of frequency v and h is Planck’s constant
then its energy in the n = 2 state will be:
(a) (E0 + hv)
(b) 2E0
(c) 4E0
(d) (E0 + 2hv)
Ans. (d)
9. A threshold wavelength of a metal is 7000 A. The work function is: (Given, velocity of light c = 3 x
108 m/s and Planck’s constant 6.624 x 10-34 J-s)
(a) 1.775 eV
(b) 17.75 eV
(c) 177.5 eV
(d) 0.8875 eV
Ans. (a)
Directions: The following items consist of two statements, one labeled the ‘Assertion (A)’ and the
other labeled the ‘Reason (R)’. You are to examine these two statements carefully and decide, if the
‘Assertion (A)’ and the ‘Reason (R)’ are individually true and if so, whether the ‘Reason (R)’ is a
correct explanation of the ‘Assertion (A)’. Select your answers to these items using the Codes given
below and mark your answer sheet accordingly:
Codes:
(a) Both A and Rare true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
 
10. Assertion (A): While traveling through air, sound waves, from two different sources, pass through
each other without being destroyed.
Reason (R): The frequency of simple harmonic waves is independent of their amplitude.
Ans. (b)
11. Assertion (A): Two ships sail parallel and close to each other during a naval exercise. To achieve
this they are to be steered slightly outwards.
Reason (R): Flow of liquid to drag in the channel produces excess pressure above the normal on the
outer sides of the ships, which pushes them inwards.
Ans. (a)
12. Assertion (A): A skater brings his hands closer to his body to spin faster.
Reason (R): Only then his moment of inertia will decrease and angular velocity will increase.
Ans. (a)
13. Assertion (A): The pressure of air inside a small soap bubble is greater than the pressure of air
inside a larger bubble.
Reason (R): The pressure of air is inversely proportional to the surface area of the bubble.
Ans. (a)
14. Assertion (A): The spherical aberration in a plano-convex lens is reduced, if its spherical surface
faces the incident parallel light.
Reason (R): In a lens spherical aberration is minimized, if the total deviation produced by a lens is
equally shared by two surfaces.
Ans. (a)
15. Assertion (A): The most common solution to the problem of eliminating chromatic aberration is
achieved with a chromatic doublet.
Reason (R): When lenses are combined to form a doublet, spherical aberration may be minimized.
Ans. (6)
16. Assertion (A): The central fringe in the reflected light of Newton’s rings between a piano-convex
lens and a plane glass plate is dark in the absence of any dust particles.
Reason (R): When a ray of light undergoes reflection at the surface of a denser medium it suffers a
phase change of it.
Ans. (a)
17. Assertion (A): A 1 mW He-Ne laser is hundred times brighter than the intensity of sunlight on
earth.
Reason (R): Laser beam is highly directional.
Ans. (a)
18. Assertion (A): At 0 K, the molecules of a gas possess no energy.
Reason (R): At absolute zero temperature the molecule of a gas possess some energy called zero
point energy
Ans. (b)
19. Assertion (A): At a given temperature radiations emitted by pin hole cavities in different materials
are different.
Reason (R): Pinhole cavities in all materials behave like perfect black body.
Ans. (d)
20. Assertion (A): If a body is in thermal equilibrium with the surroundings, then it will absorb and
emit radiant energy at the same rate.
Reason (R): Stefan-Boltzmann law is true for both emission and absorption of radiant energy
Ans (c)
21. Assertion (A): The study of Hall Effect can give the sign of charge carriers in a conductor.
Reason (R): The sign of charge carriers is determined by the sign of the Hall potential which is
 
developed in-the lateral direction of the current.
Ans. (a)
22. Assertion (A): In Stern-Gerlach experiment the single beam of silver atoms after passing through
non-homogeneous magnetic field was split into two distinct parts.
Reason (R): Space quantization permits two opposite spin directions, resulting in the deflection of the
beam in two opposite directions.
Ans. (a)
23. Assertion (A): An electron cannot be observed without changing its momentum by an
indeterminate amount.
Reason (R): Momentum of an electron is h/? where is its wavelength.
Ans. (b)
24. Assertion (A): Uniform magnetic field B has a non-zero divergence at the pole of a bar magnet.
Reason (R): Magnetic field cannot transfer energy to charged particles.
Ans. (d)
25. Assertion (A): Electrons find greater attractive forces by collector once they reach the base from
an emitter in n-p-n transistor operation.
Reason (R): The reverse bias voltage on the collector is much higher than the forward bias on the
emitter.
Ans. (a)

​

​

1. A machine gun fires n bullets per second and the mass of each bullet is m. If the speed of bullets
is v, then the force exerted on the machine gun is
(a) mng
(b) mnv
(c) mnvg
(d) mnv/ 8
Ans. (b)
2. A Diwali rocket is ejecting 0.05 kg of gases per second at a velocity of 400 ms-1.
The accelerating force on the rocket is
(a) 0 dyne
(b) 20 newton
(c) 20 kg wt
(d) sufficient data not given
Ans. (b)
3. A stretching force of 100 N is applied at one end of a spring balance and an
equal stretching force is applied at the other end at the same time. The reading
on the balance will be
(a) 200 N
(b) 100 N
(c) 400 N
(d) zero
Ans. (b)
4. Aluminium has a density of 2.7 g/cc. The mass of 15 cc of aluminium is
(a) 45 g
(b) 40.5 g
(c) 80 g
 
(d) 100 g
Ans. (b)
5. 60 cc of a liquid of relative density 1.4 are mixed with 40 cc of another liquid of
relative density 0.8. The density of the mixture is
(a) 1.16 g/cc
(b) 2.26 g/cc
(c) 11.6 g/cc
(d) 116 g/cc
Ans. (a)
6. The height of mercury which exerts the same pressure as 20 cm of water column, is
(a) 1.47cm
(b) 14.8 cm
(c) 148 cm
(d) none of these
Ans. (a)
7. The hot air balloon rises because it is
(a) denser
(b) less dense
(c) equally dense
(d) the given statement is wrong
Ans. (b)
8. A boat full of iron nails is floating on water in a lake. When the iron nails are
removed, the water level
(a) rises
(b) falls
(c) remains the same
(d) nothing can be said
Ans. (b)
9. A solid weighs 32 g f in air and 28.8 g f in water. The R.D. of the solid is
(a) 8.9
(b) 10
(c) 29.12
(d) 20
Ans. (b)
10. If the density of a metal is 8.2 g/cc, its relative density is
(a) 8.2
(b) 1/ 8.2
(c) 0.82
(d) none of these
Ans. (b)
......................................................-----------------------.......................................................

Physics Solved Objective Questions For RRB Exams
Physics Model questions Fully Solved
RRB ASM General Knowledge : Physics Solved Paper
1. A bullet of mass A and velocity B fired into a block of wood of mass C. If loss of any
mass and friction be neglected, the velocity of the system must be
(a) AB/A+C
(b) A+C/B+C
(c) AC/B+C
(d) A+B/AC
Ans. (a)
 
2. A rocket works on the
(a) first law of motion
(b) second law of motion
(c) third law of motion
(d) law of conservation of energy
Ans. (c)
3. 1 dyne is equal to
(a) 980 g wt
(b) 1/100 g wt
(c) 980 kg wt
(d) none of these
Ans. (b)
4. Two skaters A and B of mass 50 kg and 70 kg respectively stand facing each other
6 metres apart. They then pull on a light rope stretched between them. How far has
each moved when they meet?
(a) Both have moved 3 metres.
(b) A moves 2.5 metres and B moves 3.5 metres.
(c) A moves 3.5 metres and B moves 2.5 metres.
(d) A moves 2 metres and B moves 4 metres.
Ans. (c)
5. A body of mass M collides against a wall with velocity V and rebounds with the same speed. Its
change of momentum is
(a) zero
(b) MV
(c) 2MV
(d) –MV
Ans. (c)
6. A bullet in motion hits and gets embedded in a solid resting on a frictionless table.
What is conserved?
(a) Momentum and kinetic energy
(b) Momentum alone
(c) Kinetic energy alone
(d) Neither momentum nor kinetic energy
Ans. (b)
7. A man sitting in a train in motion is facing the engine. He tosses a coin up,
the coin falls behind him. The train is moving
(a) forward with uniform speed
(b) backward with uniform speed
(c) forward with acceleration
(d) forward with deceleration
Ans. (b)
8. If the mass of a body is 12.1 g and the density is 2.2 g/cc, its volume is
(a) 1.5 cm3
(b) 8 cc
(c) 11 cc
(d) 55 cc
Ans. (a)
9. Brine has a density of 1.2 g/ccc. 40 cc of it are mixed with 30 cc of water.
The density of solution is
(a) 2.11 g/ccc
(b) 1.11 g/ccc
(e) 12.2 g/ccc
 
(d) 20.4 g/ccc
Ans. (b)

​

10. If a force of 10 N acts on surfaces of areas in the ratio 1: 2. then the ratio of
thrusts is
(a) 1:2
(b) 2:1
(c) 3:1
(d) 1.1
Ans. (d)
11. The buoyant force depends on the
(a) depth of a liquid
(b) density of a liquid
(c) colour of a liquid
(d) none of these
Ans. (b)
12. A force of 50 N is applied on a nail of area 0.00 1 sq. cm. Then the thrust is
(a) 50 N
(b) 100 N
(c) 0.05 N
(d) 10 N
Ans. (a)
13. A piece of wood floats in water. What happens to it in alcohol?
(a) Floats higher
(b) Stays as before
(c) Sinks
(d) Sinks and rises
Ans. (c)
14. An ice cube is floating in a glass of water. What happens to the water level when
the ice melts?
(a) Rises
(b) Falls
(c) remains same
(d) First rises and then falls
Ans. (c)
15. The SI unit of pressure is
(a) atmosphere
(b) dyne/cm2
(c) pascal
(d) mm of Hg
Ans. (c)
16. A body of mass 50 kg has a volume 0.049 m3.The buoyant force on it is
(a) 50 kg f
(b) 50N
(e) 49N
(d) 49kg f
Ans. (d)
17. If two masses A and B have their masses in the ratio 1: 4 and their volumes are equal,
then the densities have the ratio
(a) 1:4
(b) 4:1
(c) 2:1
 
(d) 3:1
Ans. (a)
18. If the density of a block is 981 kg/m3, it shall
(a) sink
(b) float
(c) float completely immersed in water
(d) float completely out of water
Ans. (b)
19. As the density of a series of liquids increases, the upthrust on the iron rod submerged
(a) increases
(b) decreases
(c) remains constant
(d) nothing can be said
Ans. (a)
20. The SI unit of thrust is
(a) N
(b) dyne
(c) kg wt
(d) N m-2
Ans. (a)
21. The total force exerted by the body perpendicular to the surface is called
(a) pressure
(b) thrust
(c) impulse
(d) none of these
Ans. (a)
22. At sea level, atmospheric pressure is
(a) 76 cm of Hg column
(b) 76 cm of Hg column
(c) 0.76 cm of Hg column
(d) 76 cm of water column
Ans. (a)
23. Atmospheric pressure is measured by a
(a) doctor’s thermometer
(b) peedometer
(c) mercury barometer
(d) none of these
Ans. (c)
24. The weather forecasting department uses………as the unit of pressure,
(a) bar
(b) N m-2
(c) Pa
(d) mm of Hg
Ans. (a)
25. Which of the following physical quantity has no unit?
(a) Relative density
(b) Density
(c) Pressure
(d) Thrust
Ans. (a)
 
1. The magnetic field through a coil changes at uniform rate from 0.1 T to 0.4 T during 2 x 102s. If
the area of cross-section of the coil is 4 x 10-2 m2 and the number of turns is 200, then the emf
induced in the coil is:
(a) 50 V
(b) 120 V
(c) 180 V
(d) 220 V
Ans. (b)
2. A coil of N turns, made of copper wire of length 4 m is placed in a magnetic field that changes with
time. The value of N, for which induced emf will be maximum, is:
(a) 1
(b) 2
(c) 3
(d) 4
Ans. (d)
3. A current of I A is passed through a semiconductor material of thickness 1 mm. It is placed in a
transverse magnetic field of 1 T. If the earner density is 1025/m2, then the Hall potential is:
(a) 63 mV
(b) 6.3 mV
(c) 0.63 mV
(d) 0.063 mV
Ans. (c)
4. If a plane electromagnetic wave propagating in space has an electric field of amplitude 9 x 103
V/m, then the amplitude of the magnetic field is:
(a) 2.7 x 1012T
(b) 9.0 x 10-3 T
(c) 3.0 x 10-4T
(d) 3.0 x 10-5T
Ans. (d)
5. A cyclotron of radius 64 cm accelerates deuterons (m = 3.3 x 10-27 kg). If the cyclotron frequency
is 5 MHz, then the maximum speed with which the deuterons
Emerge, is
(a) 3 x 107m/s
(b) 2 x 107m/s
(c) 1.5 x 107m/s
(d) 2 x 106m/s
Ans. (b)
6. In a typical electron synchrotron, the magnetic field:
(a) Is varied with time while the radio frequency is held constant
(b) Is held constant while the radio frequency is varied with time
(c) As well as the radio frequency are varied with time
(d) As well as the radio frequency are held constant
Ans. (c)

​

7. Consider the following statements:
Stern and Gerlach experiment gives a direct and convincing confirmation of:
1. Space quantization.
2. Wave nature of electron.
 
3. Spin of electron.
4. quantized atomic magnetic moment.
Which of the above statements are correct?
(a) 3 and 4
(b) 1,2and4
(c) 1,3and4
(d) 1 and 2
Ans. (c)
8. Lionization potential for a hydrogen atom is 13.6 eV. The ionization potential for a positronium
atom where an electron revolves round a positron, is:
(b) 6.8 eV
(a) 13.6 eV’
(c) 3.4 eV
(d) 1.7 eV
Ans. (b)
9. The glancing angle in a X-rays diffraction experiment is 30° and the wavelength of the X-rays used
is 20 nm. The inter planar spacing of the crystal diffracting these X-rays will be
(b) 20 nm
(a) 40 nm
(c) 15 nm
(d) l0 nm
Ans. (b)
10. If a proton and an electron have same de-Broglie wavelength, then:
(a) Both have same kinetic energies
(b) Proton has more kinetic energy than electron
(c) Electron has more kinetic energy than proton
(d) Both have same velocity
Ans. (c)
11. Six a-decays and a number of 13-decays occur before 90Th232 achieves stability; the final
product in the chain being 82Pb208. The number of ?-disintegrations taking place is:
(a) 2
(b) 4
(c) 6
(d) 8
Ans. (b)
12. Two. Substances X and Y are made radioactive and contain equal number of atoms. X has halflife
of
1
h
and
Y
has
half-life
of
2
h.
After
a
lapse
of
2
h,
the ratio
of
the
rate
of
disintegration
of
X to
that
of
Y will
be:

(a)
1:
4

(b)
2:
1

(c)
1:
1

(d)
1:
2

Ans.
(b)

13. An unstable particle of rest energy 1000 MeV ecays into aµ-meson and a neutrino, with a mean
life time of 10-8 s, when at rest. The mean decay distance, in meters, when the particle has a
momentum of 1000 MeV/c is:
(a) 3
(b) 6
(c) 9
(d) 12
Ans. (a)
 
14. Consider the following statements about a neutron:
1. Neutron is a fermion.
2. A neutron is heavier than a proton.
3. A free neutron is an unstable particle.
Which of the above statements are correct?
(a) 1, 2 and 3
(b) 1 and 2
(c) 2 and 3
(d) 1 and 3
Ans. (a)
15. The annihilation of a slow positron and an electron cannot result into a photon, but must produce
at least two photons traveling in opposite directions. This implies conservation of:
(b) Energy
(a) Baryons
(c) Leptons
(d) Momentum
Ans. (d)
16. The energy of a particle in a potential box and that of the hydrogen atom varies with the
quantum number n, respectively, as:
(a) n2 and 1/n2
(b) 1/n2 and n2
(c) n2
(d) 2/n2 and 1/n2
Ans. (a)
17. An excited state of hydrogen atom has a life tithe of 2.5 x 10-14 s. The minimum error in the
measurement of the energy of the excited state will be:
(a) 1.656 x 10-40 erg
(b) 1.656 x 10-40 J
(c) 2.65 x 10-13erg
(d) 2.65 x 10-13J
Ans. (c)
18. If input impedance of an FET is R1, and that of a BJT is R2, then:
(a) R1>R2
(b) R1 (c) R1 = R2
(d) None of these
Ans. (a)
19. The correct sequence of the band-gaps of germanium (Eg1) silicon (Eg2) and gallium arsenide
(Eg3) will be:
(a) Eg1 > Eg2 > Eg3
(b) Eg1 < Eg2 (c) Eg2 < Eg1 < Eg3
(d) Eg2 > Eg1 > Eg3
Ans. (c)
20. The Fermi level of an intrinsic semiconductor is pinned at the centre of the band-gap. The
probability of occupation of the highest electron state in valence band at room temperature will be:
(a) Zero
(b) Between zero and half
(c) Half
(d) One
Ans. (c)

​

21. If a semiconductor has an intrinsic carrier concentration of 1.41 x 1016/m3 when doped with
1021/m3 phosphorus atoms, then the concentration of holes/m3 at room temperature will be:
(a) 2 x 1021
 
(b) 2 x 1011
(c) 1.41 x 10
(d) 1.41 x 1016
Ans. (a)
22. A n-p-n transistor circuit has ? = 0.985. If IC = 2 mA, then the value of Ib is:
(a) 0.03 mA
(b) 0.003 mA
(c) 0.66 mA
(d) 0.015 mA
Ans. (a)
23. The DC load line of an amplifier circuit:
(a) Has a positive slope
(b) Has a curvature
(c) Does not contain the Q-point
(d) Has a negative slope
Ans. (d)
24. If a transistor amplifier has a gain of 20 dB, then the ratio of output to input power is:
(a) 100
(b) 10
(c) 20
(d) 200
Ans. (a)
25. for a square-wave response (with respect to its maximum response), the rise-time of a transistor
is defined as the time duration in which its response varies from:
(a) 10% to 50%
(b) 0% to 50%
(c) 10% to 90%
(d) 25% to 75%
Ans. (c)
....................................................---------------------------------........................................................

Physics MCQ test Free online
PHYSICS Practice objective test
1. If the energy, B = G r where G is the universal gravitational constant, h is the Planck’s constant
and c is the velocity of light, then the values of p, q and r are, respectively:
(a) – ½, ½ and 5/2
(b) ½, – ½ and 5/2
(c) – ½, ½ and 3/2
(d) ½, – ½ and 3/2
Ans. (a)
2. Two bodies A and B start from rest and from the same point with a uniform acceleration of 2 m/s2
If B starts one second later, then the two bodies are separated, at the end of the next second, by:
(a) 1 m
(b) 2 m
(c) 3 m
(d) 4 m
Ans. (c)
3. A 25 kg crate, starting from rest at the top, slides down a plane that makes an angle of 30° with
the horizontal. When it reaches the bottom of the l0m long slide, its velocity is 8 m/s. The work done
by the force of friction is closest to a value of
(a) 17.0 x l02J
 
(c) 6.5 x 102J
(b) 8.0 x l02J
(d) 4.5 x 102J
Ans. (d)
4. A particle of mass 10 kg is moving in a straight line. If its displacement, x With time t is given by, x
= (t3 – 2t – 16)m, then the force acting on it at the end of 4 s is:
(a) 24N
(c) 300N
(b) 240N
(d) 1200N
Ans. (b)
5. A golf ball of mass 005 kg placed on a tee, is struck by a golf club. The speed of the golf ball as it
leaves the tee is 100 m/s. the time of contact between them is 0.02 s. If the force decreases to zero
linearly with time, then the force at the beginning of the contact is
(a) 500 N
(b) 250 N
(c) 200 N
(d) 100 N
Ans. (a)
6. The moment of a inertia of a dumb-bell, consisting of point masses m1 = 2.0kg and m2 = 1.0kg,
fixed to the ends of a – rigid massless rod of length L 0.6 m, about an axis passing through the
centre of mass and perpendicular to its length, is:
(a) 0.72 kg-m2
(b) 0.36 kg-m2
(c) 0.27 kg-m2
(d) 0.24 kg-m2
Ans. (d)
7. A merry-go-round starting from rest accelerates for 5 s with an angular acceleration of 0.4 rad/s 2
It then rotates at constant angular velocity for 30s before slowing down at the same rate. The
distance covered by a thud, sitting on a toy-horse 3 m from the centre, is:
(a) 35 m
(b) 55m
(c) 105 m
(d) 210m
Ans. (d)
8. Two springs A and B with spring constants, kA =2kB are stretched by applying forces of equal
magnitudes at their ends. If the energy stored mA is E, then the energy stored in B is.:
(a) E/4
(b) E/2
(c) E
(d) 2E
Ans. (d)
9. In a circus, a person with a mass of 70 kg stands without any floor-support against the wall of a
cylindrical rotor. If the coefficient of friction between the rotor-wall surface and the man’s feet is 0.4
and radius of rotor is 2.0 m, then the minimum angular speed of rotor such that the person does not
fall, should be:
(a) 7.0 rad/s
(b) 1.75 rad/s
(c) 3.5 rad/s
(d) 5.25 rad/s
Ans. (c)

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10. A comet moves in an elliptical orbit with an eccentricity of e = 0.20 around a star. The distance
between the perihelion and the aphelion is 1.0 x 108km. If the speed of the comet at perihelion is 81
 
km/s. then the speed of the comet at the aphelion, is:
(a) 182 km/s
(b) 36 km/s
(c) 121.5 km/s
(d) 54 km/S
Ans. (a)
11. A chair is suspended from a spring with spring constant of 600 N/m. The periodic time for
oscillation of system is 1 s. When a man sits in this chair, the periodic time becomes 2.5 s. The
weight of the man is closest to a value of:
(a) 650 N
(b) 800 N
(c) 950 N
(d) 1100 N
Ans. (b)
12. When a spring is stretched by a distance x, it exerts a force, given by F = (-5x -16×2) N. The
work done, when the spring is stretched from 0.1 m to 0.2 m, is
(a) 8.1 x 10-2J
(b) 12.2 x 10-2J
(c) 8.1 x 10-1J
(d) 12.2 x 10-1J
Ans. (a)
13. If the momentum of an electron moving with a velocity 0.9 c is increased by 1%, then the
increase in its energy is:
(a) 1%
(b) 0.9%
(c) 0.81%
(d) 0.5%
Ans. (a)
14. An inertial frame of reference B is moving along the X-axis with a velocity 9 x 106 m/s with
respect to another inertial frame A. A rod is located in the frame A with its two ends at the coordinate
points (5, -5, 0) m and (5, 7, 5) m. The length of the rod as observed from the frame B is
(a) 13.5m
(b) 13.0m
(c) 12.75 m
(d) 12.5
Ans. (b)
15. A rain drop of radius 1.5 mm, experiences a drag force, F = (2 x 10-5v) N, while falling through
air from a height of. 2 km, with a velocity V. The terminal velocity of the rain drop will be nearly:
(a) 200 m/s
(b) 80 m/s
(c) 7 m/s
(d) 3 m/s
Ans. (c)
16. Two traveling waves
y1 = 0.65 sin (0.4x – 800t) m
And y2 = -0.65 sin (0.4x + 800t) m
Are superposed in a medium. For the resultant wave at the point x = 2.5? m, the maximum
displacement is:
(a) Zero
(c) 0.65 m
(b) 1.30m
 
(d) 0.91 m
Ans. (b)
17. The maximum amplitude in the case of a forced oscillator occurs at the
(a) Natural frequency of the oscillator
(b) Frequency of the force
(c) Frequency greater than the natural frequency of the oscillator
(d) Frequency less than the natural frequency of the oscillator
Ans. (d)
18. A sound source S of frequency 1125 Hz is moving towards a stationary observer O with a speed
of 29 m/s. Then O perceives it as a frequency of v1. If s is stationary while O is moving towards S,
with the same speed, the frequency perceived by O, is v2. If the velocity of sound is 343 m/s, then v1
and v2 are, respectively:
(a) 1229; 1220
(b) 1220; 1229
(c) 1224; 1224
(d) 1224; 1232
Ans. (a)
19. The temperature in Kelvin, at which the average speed of H2 molecules will be same as that of
N2 molecules at 35° C, will be
(a) 22
(b) 42
(c) 295
(d) 495
Ans. (a)
20. Consider the following statements regarding the characteristics of entropy:
1. Entropy is a measure of disorder.
2. Entropy changes during a reversible adiabatic process.
3. Entropy of a system decreases in all irreversible processes.
4. Change in entropy for complete reversible thermodynamic cycle is zero.
Which of the above statements are correct?
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 1 and 4
Ans. (d)
21. A Carnot engine whose low-temperature reservoir is at 27°C has efficiency 37.5%. The hightemperature
reservoir
is at

(a)
480°C

(b)
327°C

(c)
307°C

(d)
207°C

Ans.
(d)

22. Colloidal particles of mass M are suspended in a gas at 300 K and 1 atm. The most probable
energy of these particles is equal to the kinetic energy of a gas molecule moving with the most
probable velocity Vp, at the temperature:
(a) 450 K
(b) 380 K
(c) 300 K
(d) 150 K
Ans. (c)

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23. In the van der Waals’ equation, the terms (a/V2) and (b) are introduced to account for the:
(a) Inter-molecular attraction and the total volume occupied by the gas
 
(b) Molecular size and the size of the containing vessel
(c) Inter-molecular attraction and the volume of the molecules
(d) Inter-molecular attraction and the force exerted by the molecules on the walls of the container
Ans. (d)
24. In the spectrum of black body radiation, the distribution of energy switches from adherence to
Planck’s law, to Wien’s law (in short Wavelength region) because of the fact that both these laws:
(a) Assume continuous variation of energy
(b) assume discontinuous Variation of energy
(c) Use the same expressions for different modes of vibration
(d) Lead to very small values for the probability factor
Ans. (b)
25. The phenomenon of viscosity in gases is associated with momentum transport from ‘high velocity’
region to ‘low velocity’ region. The mean square velocity of those molecules which participate in the
transfer of momentum across a hypothetical layer of the gas is given by:
(a) 2kT/m
(b) 8kT/m
(d) 3kT/m
(c) 4kT/m
Ans. (b)
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Solved UPSC Physics Questions
physics solved questions for UPSC IAS
Sample Test papers Model Questions physics for UPSC
1. Two organ pipes closed at one end, when blown simultaneously produce 4 beat /s. If the length of
the shorter pipe is 0.75 m, the length of the other will be (velocity of sound = 330 m/s)
(a) 1m
(b) 0.87m
(c) 0.82m
(d) 0.78m
Ans. (d)
2. Two glass slabs of thickness 6 cm and 7 cm with refractive indices 1.5 and 1.75 respectively, are
placed one above the other on an ink drop. The apparent depth of the ink drop is
(a) 8 cm
(b) 5 cm
(c) 2 cm
(d) 6.5 cm
Ans. (a)
3. A prism of glass (n = 1.5) has the prism angle as 60°. If angles of incidence and emergence at first
and second refracting faces are i1 and i2, then for minimum deviation
(a) i1 = i2
(c) i1 > i2
(b) i1 = 0
(d) i1 < i2
Ans. (a)
4. Indicate the color of light, among the following, which travels through glass with the minimum
speed:
(a) Red
(c) Yellow
(b) Green
(d) Violet
Ans. (d)
 
5. Objectives of a pair of binoculars have apertures 60 mm and focal length 250 mm. The ocular
aperture is 250mm and focal length 22 mm. The angular magnification is, approximately:
(a) 11.4
(b) 114
(c) 1140
(d) 11400
Ans. (a)
6. Two lenses separated by a distance- t and having the focal lengths f1 and f2 respectively, are
made of the same material. Then the chromatic aberration will be minimum, if t is equal to:
(a) 2 (f1 + f2)
(b) 2 (f1 – f2)
(c) (f1 – f2)/2
(d) (f1 + f2)/2
Ans. (d)
7. Spherical aberration is minimized by
1. Use of stops.
2. Use of piano-convex lens.
3. Using two suitable lenses in contact.
4. Using two piano-convex lenses separated by a distance.
Which of the above statements are correct?
(a) 3 and 4
(b) 1, 2 and 4
(c) 1, 2 and 3
(d) 1, 2, 3 and 4
Ans. (d)
8. An object of 12 mm height is placed at a distance of 80 cm to the left of a lens of power + 2.5 D
made of glass of refractive index 1.5. The size of the image is:
(a) 3mm
(b) 6mm
(c) 12mm
(d) l8mm
Ans. (c)
9. A telescope has a convex lens of focal length 100 cm as objective and a concave lens of focal
length 1 cm as eye-piece. When focused to infinity, the distance between the two lenses:
(a) Is l0l cm
(b) Is l00 cm
(c) Is 99 cm
(d) Depends on the apertures
Ans. (c)
10. A microscope has three objectives, of focal lengths
16 mm, 4 mm and 1.6 mm; an optical tube length of
16 cm and eyepieces marked 5x and l0x. The highest magnification possible is:
(a) + l000x
(b) +l0000x
(c) + 5000x
(d) + 50000 x
Ans. (c)

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11. Consider the following statements when a steel ball hits a clay chunk in air and gets embedded in
it, then
1. Both the momentum and the energy conserved.
2. Only momentum is conserved.
3. Energy is used to deform the clay chunk.
 
4. Momentum is not conserved.
Which of the above statement(s) is/are correct?
(a) l only
(b) 2 and 3
(c) 3 and 4
(d) l and 3
Ans. (b)
12. A wooden block having a mass of 1 kg is placed on a table. The block just starts to move, when a
force of 10 N is applied at 45° to the vertical to push the block. The coefficient of friction between the
table and the block, (taking g =10 m/s2) is approximately:
(a) 0.2
(c) 0.6
(b) 0.4
(d) 0.8
Ans. (d)
13. A tunnel is dug through the earth from one side to the other along a diameter. A metallic ball
having diameter smaller than the diameter of the tunnel is dropped from one side. The correct motion
of the ball is it:
(a) Executes SHM about the centre of earth
(b) Stops at the centre of the earth
(c) Freely passes out through the other end of the tunnel
(d) Does not pass through the tunnel
Ans. (a)
14. For a particle undergoing a circular motion with uniform velocity the velocity is:
(a) Radial, acceleration is radial
(b) Transverse, acceleration is radial
(c) Transverse, acceleration is transverse
(d) Radial, acceleration is transverse
Ans. (b)
15. Consider the earth to be a perfect sphere and having uniform mass distribution. R is the radius of
the earth and x is the distance from the centre of the earth. The gravitational intensity is largest
(absolute value) when x is:
(a) Zero
(c) Equal to R
(b) In between zero and R
(d) Greater than R
Ans. (c)
16. The velocity of a particle at which its mass is double its rest mass (where c is velocity of light), is:
(a) 0.75 c
(b) 0.80 c
(c) 0.85 c
(d) 0.95 c
Ans. (c)
17. What is the work done on a particle of rest mass m0 in order to increase its speed from 0.6 c to
0.8 C?
(a) 5m0c2/12
(b) 5m0c2/6
(c) 5m0c2/24
(d) m0c2/7
Ans. (c)
18. A streamline represents a fixed path followed by an orderly procession of fluid particles. If A, B
and Care any three points on a streamline and v1, v2 and v3 are the velocities of the fluid particles at
 
those points, then which one of the following statements is not correct?
(a) v1, v2 and v3 are equal to each other at all points
(b) Any particle at anytime has a velocity v1 at v2 at B and v3 at C
(c) All particles passing through A also pass through B and C
(d) v1, v2 and v3 are tangential to the direction of flow at A, B and C respectively
Ans. (a)
19. Two particles execute simple harmonic motions of the same amplitude and frequency along the
same straight line. They pass one another traveling in opposite directions, whenever their
displacement is half their amplitude. The phase difference between the two is:
(a) 2?/3
(b) ?
(c) ?/6
(d) ?/3
Ans. (a)
20. Two simple harmonic waves, when fed simultaneously to the X and Y plates of a CRO trace a
circle on the screen. Then both the waves have
1. The same frequency
2. The same amplitude
3. A constant phase difference of
Which of the above statements are correct?
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) 1, 2 and 3
Ans. (d)
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Physics Solved Quiz for UPSC
UPSC Question Paper, UPSC Sample Paper Free Online
Physics Quiz Questions for IAS, UPSC, NDA and other competitive exams
1. A heated body emits radiation which has maximum intensity at frequency Vm. If the temperature
of the body is doubled
(1) The maximum intensity radiation will be at frequency 2Vm
(2) The maximum intensity radiation will be at frequency (l/2) Vm
(3) The total emitted energy will increase by a factor of 2
(4) The total emitted energy will increase by a factor of 16
Ans. (2)
Section-B
Direction: In the following questions more than one of the answers given may be correct. Select the
correct answers and mark it according to the code.
Code:
(a) 1, 2 and 3 are correct
(b) 1. and 2 are correct
(c) 2 and 4 are correct
(d) 1 and 3 are correct

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