Refraction and Reflection Quiz

A ray of light strikes a smooth mirror at an angle of 30° to the mirror’s surface. What is the angle of reflection?

• 30°

• 60°

• 90°

• 45°

A light ray traveling in air enters a glass block at an angle of incidence of 40°. If the refractive index of glass is 1.5, what is the angle of refraction (to the nearest degree)?

• 25°

• 30°

• 40°

• 60°

The refractive index of a medium is defined as the ratio of

• The angle of incidence to the angle of refraction.

• The speed of light in vacuum to the speed of light in the medium.

• The speed of light in the medium to the speed of light in vacuum.

• The sine of the angle of incidence to the sine of the angle of refraction.

The refractive index of water is 1.33. What happens when a light ray moves from water into air at an angle greater than the critical angle?

• The light continues into the air with an increased speed.

• The light refracts at an angle equal to 90°.

• The light undergoes total internal reflection.

• The light slows down and refracts toward the normal.

A diver underwater sees the Sun at an angle of 30° to the surface. What is the angle of incidence of the sunlight in air? (Refractive index of water = 1.33)

• 22.1°

• 40.5°

• 48.6°

• 60.2°

A light ray is incident from a medium of refractive index n_1 into another medium of refractive index n_2 . Which of the following conditions must be true for total internal reflection to occur?

• n_1 > n_2

• n_1 = n_2

• The angle of incidence must be less than the critical angle.

•  n_1 < n_2 

The critical angle for a light ray passing from glass (n = 1.5) into air (n = 1.0) is closest to:

• 33.7°

• 41.8°

• 48.6°

• 60.0°

A fish at the bottom of a pond looks up and sees a circular “window” through which it can view the world above the water. What causes this effect?

• Reflection from the water surface.

• Total internal reflection of light at the water-air boundary.

• Diffraction of light waves at the water surface.

• Absorption of light waves by the water.

A light ray undergoes total internal reflection at the boundary between glass and air. If the critical angle is 42°, what could be the angle of incidence?

• 30°

• 42°

• 45°

• 60°

Which of the following best describes the conditions for total internal reflection?

• The incident angle is less than the critical angle, and the light moves from a denser to a less dense medium.

• The incident angle is equal to the critical angle, and the light moves from a less dense to a denser medium.

• The incident angle is greater than the critical angle, and the light moves from a denser to a less dense medium.

• The incident angle is 90°, and the light moves from a less dense to a denser medium.