Physics – Class 12 Practice Test 7

1. When is the wave interference strong?

When the paths taken by all of the interfering waves are independent of the coherence length

When the paths taken by all of the interfering waves are equal than the coherence length

When the paths taken by all of the interfering waves are lesser than the coherence length

When the paths taken by all of the interfering waves are greater than the coherence length

2. What will be the color of the sky in the absence of the atmosphere?

White

Dark

Blue

Pink

3. The upper part of the bi-focal lens is a convex lens while its lower part is a concave lens.

False

True

4. What is the relative refractive index of water with respect to glass?

Less than unity

Unity

Zero

More than unity

5. Calculate the refractive index of the material of an equilateral prism for which the angle of minimum deviation is 60°.

\(\frac {1}{2}\)

\(\frac {1}{\sqrt {2}}\)

\(\frac {\sqrt {3}}{2}\)

√3

6. Which one of the following is not an illustration of the scattering of light?

The white color of the clouds

The red color of danger signals

Rainbow

The blue color of the sky

7. The refraction in a water tank makes apparent depth the same throughout.

True

False

8. Which of the following is a necessary condition for total internal reflection?

The angle of incidence in the rarer medium must be greater than the critical angle for the two media

The angle of incidence in the denser medium must be lesser than the critical angle for the two media

The angle of reflection in the denser medium must be greater than the critical angle for the two media

The angle of incidence in the denser medium must be greater than the critical angle for the two media

9. On what factor does the normal shift through a refracting medium depend?

Angle of deviation

Angle of Prism

The thickness of the refracting medium

Convection

10. What causes haloes (rings) around the sun or the moon?

Dispersion

Reflection of light

Refraction of light

Total internal reflection