The Electromagnetic Spectrum

In this session we will,

• Review the electromagnetic spectrum

• Discuss the various forms of energy represented on the electromagnetic spectrum

Before we begin, let’s see what you already know………

• What is an electromagnetic wave?

• Who can define the properties of a wave, including wavelength and frequency?

Electromagnetic Waves

The Electromagnetic Spectrum

Radio Waves

• Wavelengths range from hundreds of meters to about 1 mm

• Used by antennas to transmit data, such as TV, radio, wireless networks

Microwaves

• Can pierce through fog and rain—ideal for transmitting cell phone signals

• No known object in nature that emits microwaves

• They are only known to be created by man-made technologies

Infrared Waves

• Emitted by warm bodies and absorbed by cool bodies– For example, emitted

by our sun and absorbed by our skin

• We feel as heat

• Used in technology applications such as night vision

Visible Light

• Very small part of the spectrum

• The colors of the rainbow and all the hues in between that humans can see

Ultraviolet Waves

• Radiated from hot bodies like stars, including our Sun

• We can’t see them, but our skin is sensitive to them– Sunburn from

exposure• Evidence that bees and

some birds can see UV waves; helps find food

X-rays

• Originate in nature, deep in space– From exploding nova and

supernova; also emitted by the Sun

• Can also be created by machines, like the one your doctor uses– Shoot electrons at a piece of

metal– The metal then releases x-

rays– The x-rays penetrate the body

but are blocked by bones

Gamma Rays

• Shortest frequency and highest wavelength of EM spectrum

• Can pass through all matter and have very high energy

• Can be used by doctors to kill cancer cells but can also be dangerous to the body’s other cells

Matching Game Review

Type of Wave

• Radio• Microwave• Infrared• Visible Light• Ultraviolet• X-ray• Gamma

Descriptiona) Only part of the spectrum

humans can see

b) Penetrate the body but are blocked by bones

c) Highest energy on the spectrum

d) Longest wavelength on the spectrum

e) No known object in nature emits these

f) Used by antennas to transfer data

g) Used for night vision

Review and Reflection

Type of Wave Something I learned Questions I have

Radio

Microwaves

Infrared

Visible Light

Ultraviolet

X-ray

Gamma