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1 The Electromagnetic Spectrum
1The Electromagnetic Spectrum
EM spectrum is complete spectrum of all
forms of “light”
EM wave consists of
electric fields which vibrate
magnetic fields making waves.
2
The EM spectrum consists of:
radio waves
cell phone waves
microwaves
radar waves
infrared waves
visible light waves
ultraviolet waves
x-ray waves
gamma waves
The Electromagnetic Spectrum3
The Electromagnetic Spectrum4
Properties of EM waves include speed, frequency, wavelength
Speed (c), frequency (f) and wavelength (λ) are related in the formula:
c = f x λ
All light waves travel at speed of 3 x 108 m/s in a vacuum
The Electromagnetic Spectrum5
All parts of EM spectrum travel at same speed.
λ and f have indirect relationship.
As one the other
As λ , f
The Electromagnetic Spectrum6
As wavelength decreases, frequency does what?
increases
The Electromagnetic Spectrum7
Electromagnetic wave characteristics:• short wavelengths have a high frequency
• long wavelengths have a low frequency
Electromagnetic waves & Energy:• high frequency waves have high energy
• low frequency waves have low energy
The Electromagnetic Spectrum8
The Electromagnetic Spectrum9
increasing frequency and increasing energy
If you haven’t already, sketch this drawing into
your notes. Don’t worry so much about the actual
wavelengths, just get the general shape and where
the various forms of light (radio, infrared, x-ray,
etc) exist.
smaller wavelengths have
The Electromagnetic Spectrum10
Low energy waves with longest wavelengths
Includes FM, AM, radar and TV waves
Wavelengths of 1 m (10 -1 m) and longer
Low frequency
Used in many devices such as remote control
items, cell phones, wireless devices, etc.
The Electromagnetic Spectrum11
Only radio waves are longer
Wavelength 1 x 10-1 m to 1 x 10 - 4 m (1 m to 0.001 m)
used for communication, medicine and consumer use (microwave ovens)
The Electromagnetic Spectrum12
The Electromagnetic Spectrum13
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
The portion of the EM spectrum that human
eyes can detect.
ROY G BIV (red, orange, yellow, green, blue,
indigo, violet)
Which color has the lowest frequency? red has the lowest frequency – violet the highest
The Electromagnetic Spectrum14
The Electromagnetic Spectrum15
Higher energy than light waves
Can cause skin cancer and blindness in
humans
Used in tanning beds and sterilizing
equipment
The Electromagnetic Spectrum16
High energy waves
Used in medicine,
industry and
astronomy
Can cause cancer
The Electromagnetic Spectrum17
Highest energy
Blocked from
Earth’s surface
by atmosphere
The Electromagnetic Spectrum18
The Electromagnetic Spectrum19
1. What is the relationship between
frequency and wavelength?
2. What characteristic of gamma
waves gives them their high
energy?
3. What does ROY G BIV mean?
What part of the electromagnetic
spectrum does it refer to?
The Electromagnetic Spectrum20
4. Which color is more energetic,
red or yellow?
5. Which type of wave travels faster,
gamma or radio?
6. Why are microwaves more
dangerous than radio waves?
The Electromagnetic Spectrum21
7. 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?
The Electromagnetic Spectrum22
1. Frequency and wavelength are properties of waves and since speed is constant for em waves, as frequency increases, wavelength decreases. In other words, they have an indirect relationship.
2. Gamma waves get their high energy from their extremely short wavelengths (or extremely fast frequency)
3. ROY G BIV stands for “red, orange, yellow, green, blue, indigo, and violet. They are the colors of the visible light in order of longest wavelength to shortest wavelength.
4. Yellow is more energetic than red because it has a shorter wavelength (or larger frequency)
5. Gamma waves and radio waves travel at the same speed
6. Microwaves are more dangerous than radio waves because they have a higher frequency and carry more energy.
The Electromagnetic Spectrum23
