Daily Practice Problems
Class 12 Physics
Wave Optics Question 1:

Huygen’s wave theory of light cannot explain

(a) photoelectric effect

(b) interference

(c) diffraction

(d) polarisation

Question 2:

If a source of light is moved away from a stationary observer, then the frequency of light wave appears to change because of:

(a) interference

(b) diffraction.

(c) doppler’s effect

(d) all of these

Question 3:

When seen in green light, the saffron and green portions of our National Flag will appear

(a) green

(b) black

(c) black and green respectively.

(d) green and yellow respectively.

Question 4:

Two sources of light are said to be coherent when both give out light waves of the same:

(a) amplitude and phase

(b) intensity and wavelength

(c) speed

(d) wavelength and a constant phase difference

Question 5:

The locus of all points which oscillates in phase is called __________.

(a) waves

(b) wavefront

(c) wavelets

(d) none of these

Question 6:

The penetration of light into the region of geometrical shadow is called _________.

(a) polarisation

(b) interference

(c) diffraction

(d) refraction

Question 7:

Two waves have intensity ratio 25:4. What is the ratio of maximum to minimum intensity?

(a) 16/25

(b) 25/4

(c) 9/49

(d) 49/9

Question 8:

The fringe width (β) of a diffraction pattern and the slit width d are related as:

(a) β d

(b) β 1/d

(c) β d

(d) β 1/d2

Question 9:

Define Red shift and Blue shift in Doppler’s effect.

Question 10:

When monochromatic light is incident on a surface separating two media, the reflected and refracted light both have the same frequency as the incident frequency. Explain why?

Question 11:

Two slits are made one millimetre apart and the screen is placed one metre away. What is the fringe separation when blue green light of wavelength 500 nm is used?

Question 12:

What is the value if refractive index of a medium of polarizing angle 600?

Question 13:

For what distance is ray optics a good approximation when the aperture is 3 mm wide and the wavelength is 500 nm?

Question 14:

A slit of width 3 mm is illuminated by light of λ = 600 nm at normal incidence. If the distance of the screen from the slit is 60 cm, calculate the distance between the first order minimum on both sides of central maximum.

Question 15:

Why is interference pattern nit detected, when two coherent sources are far apart? In Young’s experiment, the width of the fringes obtained with light of wavelength 6000Ǻ is 2 mm. Calculate the fringe width if the entire apparatus is immersed in a liquid medium of refractive index 1.33.

Question 16:

What are coherent sources? How does the width of interference fringes in young’s double-slit experiment change when?

(a) The distance between the slits and screen is decreased?

(b) Frequency of the source is increased?

Question 17:

The maximum intensity in Young’s double slit experiment is I0. Distance between the slits is d= 5λ, where λ is the wavelength of monochromatic light used in the experiment. What will be the intensity of light in front of one of the slits on a screen at a distance D= 10d?

Question 18:

A double slit is illuminated by light of wavelength 6000Ǻ. The slits are 0.1 cm apart and the screen is placed 1 m away. Calculate (i) angular position of 10th maximum in radian (ii) separation of two adjacent minima.

Question 19:

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

Question 20:

A slit of width ‘d’ is illuminated by white light. For what value of ‘d’ is the first minimum for red light of λ= 650 nm located at point P. For what value of the wavelength of light will be the first diffraction maxima also fall at P?

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