Objective Type Question Answers On Class 12 Physics Chapter 10

1 The focal length of the lens is 50 cm; then its power is:

A +2D

B +1D

C -2D

D -1D

View Answer

Answer:+2D

2 A phase difference of 5π corresponds to a path difference (in terms of λ) of:

A 5λ

B 10λ.

C 5λ/2

D 2λ

View Answer

Answer:5λ/2

3 Light takes 10-10 to cross a glass slab. What is the thickness of the glass slab?

A 2 cm

B 3 cm

C 2.5 cm

D 3.5 cm

View Answer

Answer:3 cm

4 In Young’s double slit experiment, a maximum is obtained when the path difference between the interfering waves is (n ∈ l):

A nλ

B

C

D

View Answer

Answer:nλ

5 Between the slit is id\ the distance between the slit and the screen is α, with light of wavelength λ, the number of fringe observed per metre on the screen is:

A δy/α

B Dα/λ

C α/Dλ

D λd/D

View Answer

Answer:δy/α

6 A person cannot see object clearly beyond 50 cm. The pow er of the lens to correct his vision is :

A +0.5 dioptre

B -0.5 dioptre

C -2 dioptre

D +2 dioptre

View Answer

Answer:-2 dioptre

7 In Young’s double slit experiment the distance between the slit and the screen is doubled and the separation between the slit is reduced to half. The fringe width:

A is doubled

B become four time

C is halfed

D remain unchanged

View Answer

Answer:become four time

8 In a double slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the slits. If the screen is moved by 5×10^-2 m towards the slits, the change in the fringe width is 3×10^-5 m. If the distance between the slits id 10^-3 m, The wavelength of the light used is:

A 5000 Å

B 3000 Å

C 4500 Å

D 6000 Å

View Answer

Answer:6000 Å

9 Light incident on a transparent medium is found to be completely plane-polarised after reflection. If the refractive index of glass plate is 1.57 then, the refracting angle of glass is:

(Given, tan^-11.57 = 57.5°)

A 15.8°

B 32.5°

C 41.6°

D None of these

View Answer

Answer:32.5°

10 A monochromatic light of wavelength 6000 Ȃ is coming from a star. What is the limit of resolution of a telescope whose objective has a diameter of 100 inch?

A 6.4 × 10^‒7 radian

B 4.1 × 10^‒7 radian

C 2.9 × 10^‒7 radian

D 1.1 × 10^‒7 radian

View Answer

Answer:2.9 × 10^‒7 radian

11 Two crossed Polaroids A and B are placed in the path of a light beam. In between these, a third Polaroid C is placed whose polarization axis makes an angle θ with the polarization axis of the Polaroid A. If I_o be the intensity of light coming out if the Polaroid A then, the intensity of light coming out of the Polaroid B is

A

B

C

D

View Answer

Answer:D

12 The polarizing angle for a medium is 60^o. The critical angle for this medium is

A sin^-1 (0.321)

B sin^-1 (0.577)

C sin^-1 (0.732)

D sin^-1 (1)

View Answer

Answer:sin^-1 (0.577)

13 A monochromatic light of wavelength 5100 Ȃ from a narrow slit is incident on a double slit. If the overall separation of 10 fringes on a screen 200 cm away is 2 cm then, the separation between the slit is

A 1.10 mm

B 0.51 mm

C 0.22 mm

D 0.11 mm

View Answer

Answer:0.51 mm

14 In young’s double slit experiment, the width of the fringes obtained when light of wavelength 6000 Ȃ is 2. 0 mm. What will be the fringe width if the entire apparatus is immersed in a liquid of refractive index 1.33?

A 0.5 mm

B 1.0 mm

C 1.5 mm

D 2.0 mm

View Answer