Waves: Practice Questions

A ray of light passes from air into a glass block. The angle of incidence is \(40^\circ\) and the angle of refraction is \(25^\circ\).
What is the refractive index of the glass?

A ray of light travels from a vacuum into a transparent glass block. The speed of light in a vacuum is \( 3.0 \times 10^8 \text{ m/s} \). If the refractive index of the glass is \( 1.5 \), what is the speed of light inside the glass block?

A sound wave travels through air at a speed of \( 330\text{ m/s} \). If the frequency of the sound is \( 165\text{ Hz} \), what is the wavelength of the wave?

A ray of light passes from air into a transparent plastic block. The angle of incidence is \(50^\circ\) and the angle of refraction is \(30^\circ\).
What is the refractive index, \(n\), of the plastic?

A ray of light is travelling inside a glass block towards an air boundary. If the critical angle of the glass is \(42^\circ\), describe the behavior of the light ray when its angle of incidence is \(45^\circ\).

The diagram shows a ray of light incident on the surface of a rectangular glass block at an angle of incidence of \(45^\circ\).
(a) State the law of reflection for a ray of light striking a plane mirror.
(b) Describe two characteristics of an image formed by a plane mirror.
(c) If the ray of light entering the glass block is refracted at an angle of \(28^\circ\), calculate the refractive index, \(n\), of the glass. Show your working.

A ray of monochromatic light travels through a glass block and meets a boundary with air at an angle of incidence of \(38.0^\circ\). The refractive index of the glass for this light is \(1.62\).

(a) Calculate the critical angle \(c\) for this glass-to-air boundary. Round your answer to one decimal place.

(b) Use your answer from part (a) to explain what happens to the light ray when it strikes the boundary at the incident angle of \(38.0^\circ\).

(c) A different ray of light is now incident on the boundary at an angle of \(45.0^\circ\). Calculate the angle of refraction in air, or explain using the concept of total internal reflection why the ray does not emerge into the air.

(d) The light wave has a frequency of \(5.0 \times 10^{14}\text{ Hz}\). Given that the speed of light in a vacuum is \(3.0 \times 10^8\text{ m/s}\), calculate the wavelength of this light inside the glass block. Give your answer in nanometres (\(1\text{ nm} = 10^{-9}\text{ m}\)).