CBSE Class 11 Physics MCQs Set 4

Question. A child pulls a toy car weighing 0.20 kg across a smooth floor by means of a string attached to it. If the string makes an angle of 60° to the floor and the child pulls with a force of 2.0 N, then the amount of work he does in pulling the car a distance of 5.0 m is...
A. 5.0 J 
B. 10.0 J
C. 12.7 J
D. 17.3 j
Answer: D

Question. The note middle C played on a piano always differs from middle C played on a violin because of a difference in...
A. frequency 
B. wavelength 
C. fundamentals
D. harmonics
Answer: D

Question. chromatic aberration of a lens is caused by...
A. diffraction 
B. diffusion 
C. dispersion 
D. interference
Answer: C

Question. The molar gas constant is the same for all gases because, at the same pressure and temperature, equal volumes of gases have the same...
A. number of molecules 
B. average kinetic energy 
C. density 
D. mass
Answer: A

Question. A Hall probe is used to determine...
A. the magnetic moment of a coil 
B. the susceptibility of a material
C. relative permittivity 
D. magnetic flux density
Answer: D

Question. In a nuclear fission reactor, graphite is often used for...
A. absorbing neutrons and controlling the reaction 
B. slowing down neutrons
C. preventing the radiation from escaping into atmosphere
D. all the above
Answer: B

Question. In a Newton's rings experiment, the thickness of the air space between the lens and the glass plate is 1.8 x 10-6 m for the sixth dark ring. The wavelength of the light used is...
A. 1.7 x 10^-8 m 
B. 3.0 x 10^-7 m 
C. 6.0 x 10^-7 m
 D. 6.0 x 10^-5 m
Answer: C

Question. If α denotes the current gain of a transistor in the common-base mode of operation and β denotes the current gain in the common-emitter mode, then α and β are related by...
A. α = β/(1 + β) 
B. α = (1 + β)/β
C. α = (1 - β)/β
D. β = (1 + α)/α
Answer: A

Question. A certain metal has a work function of 2 eV. Taking Planck's constant h = 6.6 x 10²⁴ J.s, charge on electron e = 1.6 x 10^-19 C and velocity of light C = 3 x 10⁸ m/s, what is its approximate threshold frequency?
A. 5 x 10¹³ Hz
B. 5 x 10¹⁴ Hz
C. 5 x 10¹⁵ Hz
D. 2 x 10¹⁵ Hz
Answer: B

Question. A monoatomic gas is allowed to expand adiabatically until its volume is eight times greater. Compared to the original pressure, the new pressure must be smaller by a factor of...
A. 4
B. 8
C. 16
D. 32
Answer: D

Question. During a negative β-decay...
A. an atomic electron is ejected
B. an electron which is already present within the nucleus is ejected
C. a neutron in the nucleus decays emitting an electron
D. a part of the binding energy of the nucleus is converted into an electron
Answer: C

Question. A parallel plate capacitor is charged and the charging battery is then disconnected. If the plates of the capacitor are moved farther apart by means of insulating handles...
A. the charge on the capacitor increases
B. the voltage across the plates increases
C. the capacitance increases
D. the electrostatic energy stored in the capacitor increases
Answer: D

Question. Two bodies M and N of equal masses are suspended from two separate massless springs of spring constants K₁ and K₂, respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, then the ratio of the amplitude of vibration of M to that of N is...
A. K₁/K₂ 
B. √(K₁/K₂)
C. K₂/K₁
D. √(K₂/K₁)
Answer: D

Question. Two coherent monochromatic light beams of intensities I and 4I are superimposed. The maximum and minimum intensities in the resulting beam are...
A. 5I, I 
B. 5I, 3I
C. 9I, I 
D. 9I, 3I
Answer: C

Question. A vessel contains oil (density = 0.8 g/cm³) over mercury (density = 13.6 g/cm³). A homogeneous sphere floats with half its volume immersed in mercury and other half in oil.The density of the material of the sphere in g/cm³ is...
A. 3.3
B. 6.4
C. 7.2
D. 12.8
Answer: C

Question. An organ pipe P¹ closed at one end vibrating in its first harmonic and another pipe P² open at both ends vibrating in its third harmonic are in resonance with a given tuning fork. The ratio of the length of P¹ to that of P²
A. 8 : 3
B. 3 : 8
C. 1 : 2
D. 1 : 3
Answer: B

Question. Two particles x and y have equal charges, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describe circular paths of radii R₁ and R₂, respectively. The ratio of the mass of x to that of y is...
A. (R₁/R₂)^1/2
B. R₂/R₁
C. (R₁/R₂)²
D. R₁/R₂
Answer: C

Question. A feably prepared radioactive source of half life 2 h emits radiation of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is...
A. 6 h
B. 12 h
C. 24 h
D. 128 h
Answer: B

Question. A nuclear bomb explodes 200 km above the surface of moon. The sound of explosion on the moon will...
A. be heard before the flash of explosion is seen
B. be heard at the same time explosion occurs
C. be heard after the explosion
D. not be heard at all
Answer: D

Question. A blue colour star is...
A. hotter than white star
B. cooler than white star
C. at the same temperature as white star
D. at 0 K temperature
Answer: A

Question. The position of a particle at time t is √ x = 10 + t, then...
A. velocity is constant
B. velocity α t
C. acceleration α t
D. acceleration is zero
Answer: B

Question. The maximum height and range of a projectile are equal when the angle of projection is...
A. 45
B. 60
C. tan^-1 (1/4)
D. tan^-1 4
Answer: D

Question. A force of 140 N acts on a body of mass 100 kg. If the frictional force is 40 N, then the acceleration of the body is ______ m/s²
A. 1
B. 180
C. 18
D. 1.8
Answer: A

Question. The work done by centripetal force(F) on a particle of mass m moving round a circle of radius r with a uniform sped of v is
A. F x r
B. F x 2πr
C. zero
D. F x v
Answer: C

Question. When a sphere rolls without slipping the ratio of translational kinetic energy to total kinetic energy is...
A. 3 : 7
B. 1 : 1
C. 7 : 5
D. 5 : 7
Answer: D

Question. When a satellite revolves round the earth in an orbit very close to earth its orbital velocity is...
A. 11.2 m/s
B. 11.2 km/s
C. 8 m/s
D. 8 km/s
Answer: D

Question. The diameter of a water molecule is _____ A°.
A. 1.5
B. 2
C. 1
D. 3
Answer: D

Question. To produce longitudinal extension we should exert force in...
A. one direction only
B. two directions
C. perpendicular to the body in all directions
D. parallel to the body
Answer: B

Question. A metal sphere has a spherical cavity in it. When the ball is heated the volume of cavity will...
A. Increase
B. Decrease
C. not change
D. depend on mass of sphere
Answer: A

Question. A weightless spring of force constant 5 N/m is cut into two equal halves and the two are connected in parallel. The equivalent force constant of the system in N/m is...
A. 5
B. 10
C. 15
D. 20
Answer: D

Question. Maximum reinforcement of two waves is obtained at points with phase difference of...
(a) nπ
(b) nπ/2
(c) 2nπ
(d) (2n + 1)π/2

Answer : C

Question. If 'd' is the width of slit, the diffraction is greater for...
(a) larger d, larger λ
(b) larger d, smaller λ
(c) smaller d, larger λ
(d) smaller d, smaller λ

Answer : C

Question. The SI unit of Planck's constant is...
(a) J
(b) J/s
(c) J.s
(d) J/s.K

Answer : B

Question. The energy of an electron depends on...
(a) its distance from the nucleus
(b) the diameter of the nucleus
(c) its diameter
(d) its charge

Answer : A

Question. Which of the following is not the spectral series obtained in the hydrogen spectrum?
(a) Balmer series
(b) Pascal series
(c) Pfund series
(d) Paschen series

Answer : B

Question. The conductivity of a semiconductor can be changed by adding impurities and by...
(a) changing its size
(b) changing its shape
(c) changing its density
(d) irradiation

Answer : D

Question. A body falling from rest covers a distance h/2 in the last second of its fall. Then the height h from which it falls is...
(a) 9.8 m
(b) 58.28 m
(c) 100/√ 2 m
(d) 50/√ 2 m

Answer : B

Question. The two ends of a train moving with uniform acceleration pass a certain point with velocities v₁ and v₂. The velocity with which the middle point of the train passes the same point is...
(a) √(v₁² + v₂²)/2
(b) √(v₁² - v₂²)/2
(c) √(v₂² - v₁²)/2
(d) (v₁ + v₂)/2

Answer : A

Question. The angle which the vector 3i + 4j makes with X-axis is...
(a) 30°
(b) 45°
(c) tan-1 (4/3)
(d) tan^-1 (3/4)

Answer : D

Question. Two bodies of equal mass are in uniform circular motion with the same period.If r₁ and r₂ are the radii of their circular paths then the ratio of their centripetal force is...
(a) r₁² / r²₂
(b) r²₂ / r¹₂
(c) r₁ / r₂
(d) r₂/ r₁

Answer : D

Question. A ball is dropped from a vertical height 'h' on the ground. If 'e' is the coefficient of restitution then the height to which the ball goes up after it rebounds for n-th time is...
(a) h/(eⁿ)
(b) h/(e²ⁿ)
(c) h.(eⁿ)
(d) h.(e²ⁿ)

Answer : D

Question. Water falls on the blades of a turbine at the rate of 10 kg/s from a height of 10 m. The power delivered to the turbine is...(take g = 10 m/s²)
(a) 1 W
(b) 1 kW
(c) 100 W
(d) 100 kW

Answer : B

Question. An electric fan has a blade of length l. The fan makes n rotations in one minute. The acceleration of a point on the tip of the blade is...
(a) 4π².l/n
(b) 4π².l.n²/(60 x 60)
(c) 4π².l.n²/60
(d) 4π².l/60n

Answer : B

Question. A body of mass m slides down an incline and reaches the bottom with velocity v. If a ring of same mass rolls down the same incline then the velocity of the ring at the bottom is...
(a) v
(b) 2v
(c) v/√ 2
(d) (√ 2)v

Answer : D

Question. The gravitational force between two particles of mass 2 kg each separated by a distance 2m is...
(a) 6.67 x 10^-11 N
(b) 0
(c) 3.335 x 10^-11 N
(d) 13.34 x 10^-11 N

Answer : A

Question. The period of revolution of a satellite in a circular orbit of radius r is T. The period of the same satellite in another circular orbit of radius 4r is...
(a) T/4
(b) T/8
(c) 2T
(d) 8T

Answer : D

Question. If K is Boltzmann's constant, the average kinetic energy of a molecule of a perfect gas is...
(a) 2/3 kT
(b) 2.5 kT
(c) 3.5 kT
(d) 1.5 kT

Answer : D

Question. The efficiency of a Carnot engine working between constant high temperature T₁ and constant low temperature T₂ is maximum when...
(a) T₁ and T₂ are high
(b) T₁ is high and T₂ is low
(c) T₂ is high and T₁ is low
(d) T₁ and T₂ equal

Answer : B

Question. A cooking vessel must have...
(a) high thermal conductivity and high specific heat
(b) low thermal conductivity and low specific heat
(c) high thermal conductivity and low specific heat
(d) low thermal conductivity and high specific heat

Answer : C

Question. The total energy of a particle executing SHM is 100 J.Then the maximum value of kinetic energy is...
(a) 50 J
(b) 100 J
(c) 25 J
(d) 10 J

Answer : B

Question. When a mass m is suspended from a spring its period of oscillation is one second. If the mass is reduced to m/2, the new period will be...
(a) 1 second
(b) 1/2 second
(c) √ 2 second
(d) 1/(√ 2) second

Answer : D

Question. Which of the following quantities can be considered as the fundamental quantity of a wave?
(a) Velocity
(b) Frequency
(c) Wavelength
(d) Amplitude

Answer : B

Question. In a stationary wave, strain is...
(a) maximum at node
(b) maximum at antinode
(c) minimum at node
(d) equal at nodes and antinodes

Answer : A

Question. Dimensions of momentum are...
(a) M¹L¹T¹
(b) M¹L¹T^-2
(c) M¹L^-1T^-2
(d) M¹L^-1T^-1

Answer : A

Question. When a 1-N force acts on a 1-N object that is able to move freely, the object receives...
(a) a speed of 1 m/s
(b) an acceleration of 1.02 m/s²
(c) an acceleration of 1 m/s²
(d) an acceleration of 9.8 m/s²

Answer : D

Question. The coefficient of static friction for steel on ice is...
(a) 0.1
(b) 0.1 N
(c) 0.1 Nm
(d) 0.1 N.kg^-1

Answer : A

Question. The work done in moving an object from A to B against a non-conservative force
(a) cannot be recovered by moving it from B to A
(b) does not depend on the path taken between A and B
(c) is always entirely converted in to heat
(d) disappears forever

Answer : A

Question. Car A has mass of 1000 kg and speed of 60 kmph. Car B has mass of 2000 kg and speed of 30 kmph. The kinetic energy of car A is...
(a) half that of car B
(b) equal to that of car B
(c) twice that of car B
(d) four times that of car B

Answer : C

Question. Brownian motion increases as...
(a) the particle size increases
(b) the viscosity of the medium increases
(c) the temperature increases
(d) the temperature decreases

Answer : C

Question. The equilibrium separation between the molecules corresponds to...
(a) maximum potential energy
(b) minimum potential energy
(c) zero potential energy
(d) zero kinetic energy

Answer : B