1. Aim: How can we explain the Electromagnetic Spectrum?
Do Now:
A light wave in a vacuum is traveling with a frequency of 6.2 x 1010 Hz. What is the wavelength?
v = fλ
3.0 x 108 m/s = (6.2 x 1010 Hz)λ
λ = 4.8 x 10-3 m

2. The Electromagnetic Spectrum
The speed of all waves of the EM spectrum in a vacuum is the speed of light (c).
= 3.00 x 108 m/s

5. Long Radio Waves Gamma Rays
What type of wave has the longest wavelength?
What type of wave has the shortest wavelength?
Long Radio Waves
Gamma Rays

6. About what is the wavelength of visible light?
10-7 m

7. Gamma Rays Long Radio Waves
What type of wave has the highest frequency?
What type of wave has the lowest frequency?
Gamma Rays
Long Radio Waves

8. Visible light only makes up about 2% of the EM spectrum!

9. What color light has a frequency between 6. 10 x 1014 Hz and 5
What color light has a frequency between 6.10 x 1014 Hz and 5.20 x 1014 Hz?
What color light has a frequency between 5.03 x 1014 Hz and 4.82 x 1014 Hz?
GREEN
ORANGE

10. In a vacuum, a monochromatic beam of light has a frequency of 6
In a vacuum, a monochromatic beam of light has a frequency of 6.3 x 1014 Hz. What color is the light?
BLUE

11. Finding Frequency or Wavelength of an Electromagnetic Wave
Use the equation
v = fλ
Just remember that any EM wave has a velocity of….
3.00 x 108 m/s
Hence, c = fλ

12. Determine the color of a ray of light with a wavelength of 6
Determine the color of a ray of light with a wavelength of 6.21 x 10-7 m.
c = fλ
(3.00 x 108 m/s) = f(6.21 x 10-7 m)
f = 4.83 x 1014 Hz
(ORANGE)

13. When asked to refer to a specific color’s frequency, choose the value to the LEFT of that color!

14. What is the wavelength of red light?
c = fλ
3 x 108 m/s = (4.82 x 1014 Hz) λ
λ = 6.2 x 10-7 m

15. Calculate the wavelength of WPLJ (95.5 fm)
c = fλ
Hint: fm radio transmits in megahertz
(3.00 x 108 m/s) = (95.5 x 106 Hz) λ
λ = 3.14 m

16. In a vacuum, all electromagnetic waves have the same
Wavelength
Frequency
Speed
amplitude

17. A 2. 00 x 106 Hz radio signal is sent a distance of 7
A 2.00 x 106 Hz radio signal is sent a distance of 7.30 x 1010 meters from Earth to a spaceship orbiting Mars. Approximately how much time does it take the radio signal to travel from Earth to the spaceship?
4.11 x 10-3 s
2.43 x 102 s
2.19 x 108 s
1.46 x 1017 s

18. How long does it take light to travel from the Sun to the Earth?