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Lesson 3: Light and Electromagnetic Waves
A) Electromagnetic Waves
a) Electromagnetic waves are radiant
energy (traveling in waves)
b) Speed of Light is 186,000 miles per
second, in a vacuum
2) Radio waves: longest wavelength in
the electromagnetidc spectrum. Are
used for radio, TV, WiFi, etc.
3) Microwaves: used by microwave
ovens to heat food
4) Infrared: Heat Energy, most object
give off energy as infrared. (Greater
than red)
5) Visible light: Red is the longest wavelength
and Purple is the shortest wavelength (Roy G.
BIV)
6) Ultra Violet (UV): shorter than visible light,
honeybees can see in UV light. It can cause skin
cancer and sunburns. (below violet)
7) X-rays: short wavelengths that pass
the body except bones
8) Gamma Rays: shortest wavelength, high
energy used in nuclear technologies
B) Reflection and Refraction
1) Reflection is the bouncing of light
waves off a surface
a) Each color has a different wavelength
b) White light is the reflection of all
colors
c) Black objects absorb all colors. NO
color is reflected back .
d) Each color only reflects one wavelength.
The rest are absorbed. For example blue
objects absorb all colors except blue. The
bue light is reflected back to us.
2) Refraction is the bending of light waves when
it passes from one medium to another
a) Example: light passing through a
prism, straw in a glass or water
C) Transparent, Opaque, Translucent
1) Transparent: medium or substance
that light can travel through
a) Examples: air, water, clear glass, clear
plastics
2) Opaque: Substances that light cannot
travel through
a) Examples: wood, pottery, bricks,
animals, people
3) Translucent: a medium that scatters light as it
pass through, so object cannot be seen clearly
a) Examples: frosted glass, stained glass,
colored plastics