Electromagnetic Waves

Chapter 12

What is an Electromagnetic Wave?

• Electromagnetic wave – is made by vibrating electric charges and can travel through space– No medium is needed…

What is an Electromagnetic Wave?

• Electromagnetic wave – is made by vibrating electric charges and can travel through space– No medium is needed…

• Electric and magnetic fields are related forces.1. A moving electric charge creates a magnetic field2. Changing magnetic fields create changing

electric fields and vice versa

Electromagnetic Fields• Carry radiant energy• Electromagnetic waves travel in a vacuum

(empty space) at 300,000 km/s– they slow as they travel through matter

The Electromagnetic Spectrum• Radio waves• Infrared waves• Visible light

• Ultraviolet light• X rays and gamma rays

Uses of Electromagnetic Spectrum

• Radio waves - Microwaves, Radar, and Magnetic Resonance Imaging (MRI)

• Infrared waves – felt as thermal energy or warmth• Visible light – duh… we see with this light• Ultraviolet waves – kill bacteria and can be absorbed

by fluorescent materials and released as visible light• X rays and gamma rays – provide images of bones,

examines within materials, radiation therapy

Radio Communication

• Radio converts electromagnetic waves into sound waves

Television

• Sounds and images changed into electronic signals broadcast by carrier waves– Carrier wave – a specific frequency in which each

channel is assigned (used in radio too)

Telephones

• Microphone converts sound waves into electrical signal.