MAP TAP 2003-2004 The Electromagnetic Spectrum 1

The Electromagnetic

Spectrum

Wavelength/frequency/energy

MAP TAP 2003-2004 The Electromagnetic Spectrum 2

Teacher Page

• Content: Physical Science—The

Electromagnetic Spectrum

• Grade Level: High School

• Creator: Dorothy Walk

• Curriculum Objectives: SC 1; Intro

Phys/Chem IV.A (waves)

MAP TAP 2003-2004 The Electromagnetic Spectrum 3

MAP TAP 2003-2004 The Electromagnetic Spectrum 4

What is it?

• The electromagnetic spectrum is the complete

spectrum or continuum of light including radio

waves, infrared, visible light, ultraviolet light, X-

rays and gamma rays

• An electromagnetic wave consists of electric and

magnetic fields which vibrates thus making

waves.

MAP TAP 2003-2004 The Electromagnetic Spectrum 5

Waves

• Properties of waves include speed, frequency

and wavelength

• Speed (s), frequency (f) and wavelength (l) are

related in the formula l x f = s

• All light travels at a speed of 3 s 108 m/s in a

vacuum

MAP TAP 2003-2004 The Electromagnetic Spectrum 6

Wavelength, Frequency and

Energy

• Since all light travels at the same speed, wavelength and frequency have an indirect relationship.

• Light with a short wavelength will have a high frequency and light with a long wavelength will have a low frequency.

• Light with short wavelengths has high energy and long wavelength has low energy

MAP TAP 2003-2004 The Electromagnetic Spectrum 7

MAP TAP 2003-2004 The Electromagnetic Spectrum 8

Radio waves

• Low energy waves with long wavelengths

• Includes FM, AM, radar and TV waves

• Wavelengths of 10-1m and longer

• Low frequency

• Used in many devices such as remote control

items, cell phones, wireless devices, etc.

MAP TAP 2003-2004 The Electromagnetic Spectrum 9

MAP TAP 2003-2004 The Electromagnetic Spectrum 10

Microwaves

• Longer than radio, shorter than light and infrared

• Wavelength 1 x 10 - 4 m to 1 x 10-1 m

• First used in radar, now used in communication, medicine and consumer use (microwave ovens)

MAP TAP 2003-2004 The Electromagnetic Spectrum 11

MAP TAP 2003-2004 The Electromagnetic Spectrum 12

Infrared waves

• Invisible electromagnetic waves that are detected as heat

• Can be detected with special devices such as night goggles

• Used in heat lamps

• Higher energy than microwaves but lower than visible light

MAP TAP 2003-2004 The Electromagnetic Spectrum 13

MAP TAP 2003-2004 The Electromagnetic Spectrum 14

Visible Light

• The portion of the electromagnetic spectrum

that human eyes can detect

• ROY G BIV (red, orange, yellow, green, blue,

indigo, violet)

• Red is the lowest frequency and violet is the

highest frequency

MAP TAP 2003-2004 The Electromagnetic Spectrum 15

MAP TAP 2003-2004 The Electromagnetic Spectrum 16

Ultraviolet waves

• Higher energy than light waves

• Can cause skin cancer and blindness in

humans

• Used in tanning beds and sterilizing

equipment

MAP TAP 2003-2004 The Electromagnetic Spectrum 17

MAP TAP 2003-2004 The Electromagnetic Spectrum 18

X-Rays

• High energy waves

• First discovered by

Roentgen

• Used in medicine,

industry and astronomy

• Can cause cancer

MAP TAP 2003-2004 The Electromagnetic Spectrum 19

MAP TAP 2003-2004 The Electromagnetic Spectrum 20

Gamma rays

• Highest energy

• Blocked from Earth’s surface

by atmosphere

MAP TAP 2003-2004 The Electromagnetic Spectrum 21

MAP TAP 2003-2004 The Electromagnetic Spectrum 22

MAP TAP 2003-2004 The Electromagnetic Spectrum 23

Time to think…..

• 1. What is the relationship

between frequency and

wavelength?

• 2. What is meant by ‘spectrum’?

• 3. What does ROY G BIV mean?

MAP TAP 2003-2004 The Electromagnetic Spectrum 24

Now, let’s really think

• 4. Can you actually see x-rays?

– Support your answer.

• 5. Which color is more energetic, red

or yellow?

• 6. Which type of wave travels faster,

gamma or radio?

• 7. Why are microwaves more

dangerous than radio waves?

MAP TAP 2003-2004 The Electromagnetic Spectrum 25

Think about it….

• You have just been involved

in a traffic incident that

leaves you stranded on the

side of the road. Which part

of the electromagnetic

spectrum would be of the

most use to you and why?

MAP TAP 2003-2004 The Electromagnetic Spectrum 26

Answers

• 1. Frequency and wavelength are properties of waves and since speed is constant for em waves, as frequency increases, wavelength decreases.

• 2. Spectrum is a continuum of all electromagnetic waves

• 3, ROY G BIV is the difference colors of the visible light in order of longest wavelength to shortest wavelength.

• 4. X-rays can not be seen, only the waves in the visible light portion are visible.

• 5. Yellow is higher energy than red because it has a shorter wavelength and higher frequency.

• 6. Both travel at the same speed, 300,000 km/s (all em waves travel at the same speed)

• 7. Microwaves have a higher frequency than radio and carry more energy.