In a CD player, light from a laser diode enters a plastic disc and reflects from a layer of shiny aluminum. Before it enters the plastic, the laser light has a wavelength of 780 nanometers and a frequency of 385,000,000,000,000 Hz. Once this light is inside the plastic, its wavelength
A) stays the same but its frequency becomes higher.
B) becomes shorter but its frequency stays the same.
C) becomes longer but its frequency stays the same.
D) stays the same but its frequency becomes lower.

Question

Quizplus · Accepted Answer

The speed of light in a medium is lower than in a vacuum, causing the wavelength to shorten while the frequency remains constant, as frequency is determined by the source (in this case, the laser diode) and does not change when light enters a different medium.

In a CD Player, Light from a Laser Diode Enters