Wave Theory of Light
Light behaves as a transverse electromagnetic wave. It can be reflected, refracted, and absorbed. Understanding the wave properties of light explains everyday optical phenomena.
What You Need to Know
Key Concept Diagram
Light travels as a transverse electromagnetic wave at 3 x 10^8 m/s in a vacuum
The electromagnetic spectrum includes radio waves, microwaves, infrared, visible light, UV, X-rays, and gamma rays
Reflection: the angle of incidence equals the angle of reflection
Refraction occurs when light changes speed as it passes from one medium to another, causing it to bend
Key Vocabulary
Electromagnetic spectrum
The complete range of electromagnetic radiation, from radio waves to gamma rays
Reflection
The bouncing of light off a surface; angle of incidence = angle of reflection
Refraction
The bending of light as it changes speed when passing from one medium to another
Wavelength
The distance between successive crests of a wave; determines colour in visible light
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
A ray of light hits a flat mirror at 30 degrees to the normal. At what angle does it reflect?
Question 2
Why does a straw appear bent when placed in a glass of water?
Question 3
Which part of the electromagnetic spectrum has the shortest wavelength and highest energy?
Key Concepts Summary
- ●Light travels as a transverse electromagnetic wave at 3 x 10^8 m/s in a vacuum
- ●The electromagnetic spectrum includes radio waves, microwaves, infrared, visible light, UV, X-rays, and gamma rays
- ●Reflection: the angle of incidence equals the angle of reflection
- ●Refraction occurs when light changes speed as it passes from one medium to another, causing it to bend