1. Characteristics of Light
By Arianna Lammers and Zeke DuPree

2. Overview
• Electromagnetic Wave
• How to calculate the frequency or
wavelength of electromagnetic radiation
• Recognize that light has a finite speed
• Describe how the brightness of light
source is affected by distance

3. Introduction
In this lesson, we will learn about the
Electromagnetic Spectrum, the frequency
and wavelength of the Spectrum, and
how distance affects light!

4. What is the Electromagnetic
Spectrum?
Radio Waves
• Types of Transmitters(depending on
wavelength)
• Main uses: communication
● Dangers: Large doses are believed to
cause cancer

5. What is the Electromagnetic
Spectrum?
•
Microwaves
Extremely high frequency radio waves
● Main uses: cooking, mobile phones,
speed cameras, and radars
● Dangers: cataracts and affect parts of
your brain
Should you worry about using your phone
now?

6. WARNING!!!
DON’T MAKE A HABIT OF PRESSING YOUR
FACE TO THE MICROWAVES DOOR!!!

7. What is the Electromagnetic
Spectrum?
Infrared
● Infra means “below”. Infrared is
below visible red light
● Main uses: remote controls, heal
sport injuries, night sight, and
thermal sighting
● Danger- OVERHEATING!

8. What is the Electromagnetic
Spectrum?
•
•
Light
Tiny part and visible light
Main uses: See things, laser, Laser
printer, and weapon aiming systems
● Dangers: Damage your retina

9. What is the Electromagnetic
Spectrum?
•
Ultraviolet
Given off by the sun
● Main uses: Sun tan, detecting forged bank
notes, and kills microbes
● Dangers: Damage the retina, sunburns
and skin cancer

10. What is the Electromagnetic
Spectrum?
•
•
•
X-Rays
High frequency waves and carries
a lot of energy
Main uses: See inside people,
airport security, and astronomers
Dangers: Cell damage and cancer

11. What is the Electromagnetic
Spectrum?

12. What is the Electromagnetic
Spectrum?
Gamma Rays
● Stars and radioactive substancesdifficult to stop
● Main uses: Kill cancer cells,
radiotherapy, tracers, and,targeted
radiotherapy
● Dangers: Cell damage and mutations

13. Components of the
Electromagnetic Spectrum

14. Calculating Frequency of
Electromagnetic Radiation
λν = c
What is the frequency of infrared radiation of
wavelength 67.5 μm?
1) Convert μm to m
67.5 μm = 67.5 x 10-6 m
2) Use λν = c to determine the frequency:
(67.5 x 10-6 m) (x) = 3.00 x 108
m/s
x = 4.44 x 1012 s-1

15. Calculating wavelength of
Electromagnetic Radiation
λν = c
When an electron beam strikes a block of copper, xrays of frequency 1.07 x 1019 Hz are emitted. What
is the wavelength of these x-rays? Answer in units
of pm.
1) Substitute into λν = c:
(x) (1.07 x 1019 s¯1) = 3.00 x 108 m s¯1
x = 2.80 x 10¯11 m
2) Convert from m to pm:
2.80 x 10¯11 m x (1012 pm / 1 m) = 28 pm

16. Light has finite speed
• 300,000,000 m/s is the speed of light.
• Light is an electromagnetic wave
● A wave takes time to get from one point
to another
● Infinite light: would have to be
everywhere at once unlike a wave

17. Brightness of Light Source is Affected by
Distance
Scientist have calculated that when distance
doubles, the brightness of the sources is
decreased by a factor of four.
I=
2
C/d
The C in the equation represents the
constant of the wattage of your source.

18. These waves are used to inspect luggage in
airport security
Review!
These waves have the
longest wavelength in
the EM spectrum
X-Rays
Radio
Waves
Used for mobile phones and radar
The highest frequency waves in the EM
spectrum
Gamma
Rays
The waves used for TV remote controls
Microwaves
These waves make your gin &
Infrared
tonic glow. (If you're old enough Emitted by the laser in CD & DVD drives
for alcohol, anyway.)
Ultraviolet
Light

19. Any Questions??

20. Bibliography
Brightness and Distance. (n.d.). Brightness and Distance. Retrieved October 25, 2013, from
http://cosmology.berkeley.edu/Education/Projects/Desktop_Stars/DTS/ISQ/Discussion.html
Calculate the frequency when given the wavelength. (n.d.). Calculate the frequency when given the
wavelength. Retrieved October 25, 2013, from http://www.chemteam.info/Electrons/calc-freq-givenwavelength.html
Reucroft, S., & Swain, J. (n.d.). Why isn't the speed of light infinite?: Scientific American. Why isn't the
speed of light infinite?:
Scientific American. Retrieved October 25, 2013, from
http://www.scientificamerican.com/article.cfm?id=why-isnt-the-speed-of-lig
Science and Nature: TV and Radio Followup. (n.d.). BBC News. Retrieved October 25, 2013, from
http://www.bbc.co.uk/sn/tvradio/programmes
The Electromagnetic Spectrum: Home page. (n.d.). The Electromagnetic Spectrum: Home page. Retrieved