Electromagnetic
Waves
 EM
waves – waves that DO NOT need a
medium to travel through, they can
travel through a vacuum (empty space)
 Examples
of EM waves:
•
Radio waves – GPS, MRI, RADAR
•
Microwaves – heating up food
•
Infrared waves – heat lamps, warmth
•
Light – what we can see
•
Ultraviolet rays (UV) – causes cancer and vitamin D
•
X-rays – too much exposure can cause cancer
•
Gamma rays – radiation, hulk, nuclear weapons
EM Waves
 ALL
EM waves travel at the speed of light
(VERY FAST)
 At
this speed, they can travel around the
would 8 times in one second
EM Spectrum
 EM
Spectrum – range of EM waves from
low to high frequency
EM Spectrum
EM Spectrum
Longest wavelength
Shortest wavelength
Lowest frequency
Highest frequency
EM Spectrum
Visible Light
 Visible
Light – part of the EM spectrum
that humans can see
ROYGBIV
Long wavelength
Short wavelength
Low frequency
High frequency
Low energy
High energy
COLD
HOT
ROYGBIV

The color you see is the wavelength that is reflected
while all other color wavelengths are absorbed

EX: If you see green, that means green is reflected and
all other colors are absorbed – plants have chlorophyll
ROYGBIV
 White
is the reflection of all the colors
 Black
is the absorption of all the colors
Questions
1. Which EM wave has the longest
wavelength?
Radio waves
Questions
2. Which EM wave has the highest
frequency?
Gamma waves
Questions
3. What part of the EM spectrum
can be seen by humans?
Visible Light
Questions
4. Visible waves have a higher
frequency than what other waves?
Radio, Microwave, Infrared waves
Questions
5. What color of the visible light spectrum
is considered to be the hottest with the
highest energy and highest frequency?
Violet
Questions
6. In a vacuum, all EM waves
have the same?
A. Wavelength
B. Frequency
C. Speed of light
D. Amplitude
Questions
7. In the summer, people use sunscreen
to prevent damage to the
integumentary system. What type of
rays do sunscreen help prevent from
penetrating in and damaging your skin?
A. Gamma rays
B. Ultraviolet rays
C. Visible rays
D. X-rays
Questions
8. EM waves can transfer energy
without a?
A. Electric current
B. Medium
C. Magnetic field
D. Source