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Chapter 23 Wave Optics

Total questions: 12

Worksheet time: 21mins

Name
Class
Date
1.

In Young's two-slit experiment, a source of green light is used. The separation of fringes in the interference pattern produced can be increased by increasing

a)

the distance between the screen and the slit

b)

the size of every slit

c)

the distance between the two slits

d)

the intensity of the green light

2.

The figure shows the diffraction pattern by a single slit which have a slit size of 0.017 mm and is placed 80 cm from the screen. The light used has a wavelength of 600 nm. What is the width of the central bright band?

a)

5.65 cm

b)

6.65 cm

c)

7.21 cm

d)

8.34 cm

3.

A diffraction grating with 2400 lines per centimetre is used to produce a diffraction pattern that is recorded by a detector. The first-order fringe is 8.94 cm from central fringe. If the distance between the grating and the detector is 0.625 m, what is the wavelength of the electromagnetic wave used?

a)

295 nm

b)

590 nm

c)

1180 nm

d)

1190 nm

4.

A diffraction grating that has 2000 slits per centimetre is used to measure the wavelengths emitted by hydrogen gas. At what angle in the first order spectrum would you expect to find the violet line that has a wavelength of 434 nm?

a)

3°3\degree

b)

5°5\degree

c)

7°7\degree

d)

9°9\degree

5.

A plane polarized light is passed through a polaroid. The polarisation axis of the polaroid is adjusted until the intensity of the light passing through it is at maximum value

 ImaxI_{\max} . Through what angle must the polaroid be rotated so that the intensity of light that passes through it is 35% of  ImaxI_{\max}  ? 

a)

 33.1°33.1\degree  

b)

 42.6°42.6\degree  

c)

 53.7°53.7\degree  

d)

 64.8°64.8\degree  

6.

Two stars are just barely resolved by a telescope with a lens diameter of 0.500 m. Determine the angular separation of the two stars. Assume incident light of wavelength is 500 nm.

a)

1.22×106 rad1.22\times10^{-6}\ rad

b)

2.44×106rad2.44\times10^{-6}rad

c)

3.66×106rad3.66\times10^{-6}rad

d)

4.88×106rad4.88\times10^{-6}rad

7.

The figure shows monochromatic light of wavelength,  λ\lambda which is illuminated nearly normal onto a thin soap film of thickness, t and refractive index, n. The optical path difference between the reflected rays from the upper and lower surfaces of the soap film is

a)

 2tn\frac{2t}{n}  

b)

 2nt2nt  

c)

 2tn+λ2\frac{2t}{n}+\frac{\lambda}{2}  

d)

 2nt+λ22nt+\frac{\lambda}{2}  

8.

A beam of light which consists of two different wavelength λ1\lambda_1 and  λ2\lambda_2 , ( λ1>λ2\lambda_1>\lambda_2  ) is incident normally on a piece of diffraction grating. The second order line for  λ1\lambda_1  and the third order line for  λ2\lambda_2  overlap. What is the ratio of  λ1λ2\frac{\lambda_1}{\lambda_2}  ?

a)

1.5

b)

2.0

c)

2.5

d)

3.0

9.

A binary star is observed with a telescope. A coloured filter is used to maximise the resolution. (A filter of a given colour transmits only that colour of light). What colour filter would give the greatest increase in the resolution?

a)

Blue

b)

Green

c)

Yellow

d)

Red

10.

The Rayleigh criterion for resolving power for a circular aperture is

 θ=1.22 λD\theta=1.22\ \frac{\lambda}{D} . Two sources of radio waves are at a distance of 1 ×1012\times10^{12} m from the Earth. The sources are separated by 2 ×109\times10^9 m and emit radio waves of wavelength 0.03 m. What is the estimate for the diameter of a dish of a radio telescope on the Earth that will just resolve the two sources?

a)

 4×105m4\times10^{-5}m  

b)

 4×104m4\times10^{-4}m  

c)

0.018 m

d)

18 m

11.

A beam of plane-polarised light is sent through two polarisers, the first at  60°60\degree to the original plane of polarisation and the second at  90°90\degree to the original plane of polarisation. What fraction of the original polarised intensity passes through the second polariser? 

a)

0

b)

 14\frac{1}{4}  

c)

 18\frac{1}{8}  

d)

 316\frac{3}{16}  

12.

Light travelling along the core of an optical fibre, with a speed of 1.82  ×108 m s1\times10^8\ m\ s^{-1} meets the boundary with the cladding. The speed of light in the cladding is 1.89 

 \times10^8\ m\ s^{-1} . What is the minimum angle of incidence for the light in the core for it to undergo total internal reflection at the core-cladding interface?

a)

4.0 °\degree  

b)

8.0 °\degree  

c)

37.2 °\degree  

d)

74.4 °\degree