Class 12

1. Electromagnetic
Spectrum
Unit 9 - Light & Sound

2. Lesson 3: Questions
● How do the waves in the EM spectrum differ
from each other?
● How do we utilize each type of wave in the
EM spectrum?

3. Vocabulary
Define the following vocabulary words:
● Light
● Electromagnetic spectrum
● Radio waves
● Infrared
● Visible light
● Ultraviolet
● X-ray
● Gamma ray

4. Video: Electromagnetic Spectrum

5. Light
Light Energy - Energy that travels in the form
of waves.
○ Example: Sunlight

6. Light
Light - a transfer of energy that creates a
visual sensation
● Light is a transverse wave

7. Light
● Light does not need a medium to travel

8. Light
Frequency - the number of waves passing a
point per second
● Units: Hertz (Hz)
● Frequency describes the color/type of
light
HIGH frequency = Ex. UV Light Waves
LOW frequency = Ex. Radio Waves

9. Light
Light belongs to a larger category of waves
called the electromagnetic spectrum.
Electromagnetic spectrum - the full range of
visible and invisible waves.

10. Light
The electromagnetic spectrum includes:
● Radio waves
● Microwaves
● Infrared waves (IR)
● Visible light
● Ultraviolet waves (UV)
● X-Rays
● Gamma rays
All waves travel 300,000 km/s = SPEED OF LIGHT

11. Electromagnetic Spectrum
Wavelength
Frequency
Energy
Radio
(Microwaves, Radio, TV)
Infrared
(IR)
Ultraviolet
(UV)
X-Ray Gamma
Visible
Light
R
O Y G B I
V
Wavelength
Frequency
Energy
LONG
LOW
LOW
SHORT
HIGH
HIGH

12. Electromagnetic Spectrum
Radio Waves - used in radio and TV,
microwave ovens, and radar.
● Amplitude modulation (AM)
● Frequency modulation (FM)

13. Electromagnetic Spectrum
Microwaves - the shortest-wavelength radio
waves
● Cooking and reheating food
Radar Waves - waves reflect off objects and
return back towards the source they came from
● Doppler Effect
Television Waves - carry information for
pictures and sound

14. Electromagnetic Spectrum
Infrared Light (IR) - source of heat and used to
discover heat differences
● Warming lamps
● Thermograms

15. Electromagnetic Spectrum
Video: Infrared

16. Electromagnetic Spectrum
Visible Light - only light visible to humans
● Color (ROYGBIV)

17. Electromagnetic Spectrum
Ultraviolet Light - higher frequency than violet
● Sunlight (source of Vitamin D)
○ Excessive exposure damages skin
● Can disinfect air/bacteria

18. Electromagnetic Spectrum
X-Rays - makes pictures of the inside of solid
objects
● X-Ray technology

19. Electromagnetic Spectrum
Gamma Rays - high energy waves with the
greatest penetrating ability of all waves.
● Radiation therapy

20. Additional Video Resources
Click on the link below to view videos on each
of the electromagnetic spectrum waves.
Click here to learn more