Waves：練習問題

A wave on a string has a frequency of 15 Hz and a wavelength of 0.80 m. How long does it take for a single wavefront to travel a distance of 60 m?

Which of the following describes the conditions required for total internal reflection to occur in an optical fiber?

A scientist identifies an unknown electromagnetic radiation that has a shorter wavelength than visible light but does not cause mutations in the DNA of skin cells like gamma rays do. To which part of the electromagnetic spectrum is this radiation most likely to belong?

A ray of light enters a rectangular glass block from air. The angle of incidence is \(52^{\circ}\) and the angle of refraction is \(31^{\circ}\). What is the critical angle for this glass when in contact with air?

A source of sound moves away from a stationary observer at a constant speed. Which row correctly describes the change in the observed wavelength and frequency of the sound?

A ray of light travels from a glass prism towards the air-glass boundary. If the refractive index of the glass is \(1.6\), calculate the critical angle \(c\) for this boundary.

Explain why a stationary observer hears the pitch of a siren decrease as an emergency vehicle passes them and moves away at high speed.

A light ray enters a block of transparent material from air with an angle of incidence of \(45^\circ\). If the angle of refraction inside the block is \(28^\circ\), calculate the refractive index of the material.

A ray of light travels from air into a rectangular glass block. The angle of incidence at the air-glass boundary is \(35^{\circ}\) and the angle of refraction is \(22^{\circ}\).

(a) Calculate the refractive index of the glass. Give your answer to two decimal places.
(b) The ray then reaches the other side of the block where it meets a glass-air boundary. Calculate the critical angle for the glass.
(c) State what happens to the ray if it hits the second boundary at an angle of incidence of \(45^{\circ}\).