CBSE Class 11 Physics MCQs Set 12

1. 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

2. 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

3. chromatic aberration of a lens is caused by...

A. diffraction B. diffusion C. dispersion D. interference

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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)

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. The diameter of a water molecule is _____ A°.

A. 1.5

B. 2

C. 1

D. 3

28. 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

29. 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

30. 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