# Chapter 14 - Electromagnetic Waves

1.    State the properties which are common to all forms of electromagnetic radiation.

• All are transverse waves.
• All travel with the same speed, 3 x 10^8 m/s in vacuum.
• They all obey the wave equation:
• They can be reflected or refracted
• They transports energy.

2.    How do the frequency, wavelength and speed of electromagnetic waves change when it enters from air to glass?

• When an EM wave enters glass, its speed is slowed down while its frequency remains constant.
• Since, the wavelength will decrease too.

3.    State one difference between waves of red light and waves of blue light.

• Red light has a longer wavelength (or lower frequency) than blue light.

4.    State 3 ways in which an electromagnetic wave differs from the sound wave.

Sound waves

• Longitudinal waves
• Travel at an approximate speed of 330m/s through air
• Needs a medium to travel, cannot travel through vacuum

Electromagnetic waves

• Transverse waves
• Travel at an approximate speed of 3 x 10^8 m/s through air
• Does not need any medium to travel. Can travel through a vacuum