Electromagnetic Waves Notes
 Electromagnetic waves are transverse waves that do not need a medium to
travel through
o This means they can travel in space
 The transfer of energy as electromagnetic waves is called radiation
 Electromagnetic waves have a wide range of wavelengths, frequencies and
energies
 The arrangement of electromagnetic waves according to their wavelengths
is called the Electromagnetic Spectrum
 Remember: speed = wavelength x frequency
o As the wavelength increases (gets longer), the frequency decreases
(gets lower)
o As the wavelength decreases (gets shorter), the frequency increases
(gets higher)
 Waves with the longest wavelength have the lowest frequencies and the
lowest energy
 Waves with the shortest wavelengths have the highest frequencies and the
highest energy
Radio Waves
-longest wavelengths
-lowest frequencies and energy
-examples: radio, tv, radar
Microwaves
-2nd longest wavelengths
-2nd lowest frequency and energy
-examples: microwave ovens, cell phones
Infrared
-heat waves
-3rd longest wavelengths
-3rd lowest frequency and energy
-examples: tv remotes, heat lamps
Visible light
-only EM wave we can see
-middle of the spectrum
-ROY G BIV (red, orange, yellow, green, blue, indigo, violet) in order from
the longest wavelength to the shortest (infrared is before red and ultraviolet is
after violet!)
Ultraviolet
-3rd shortest wavelength
-3rd highest frequency and energy
-too much can cause sun burn
-examples: black lights, sterilizers
X-rays
-2nd shortest wavelengths
-2nd highest frequencies and energy
-can pass through skin but bot bone or metal
Gamma Rays
-shortest wavelength
-highest frequency and energy
-most penetrating and dangerous of all the waves
-examples: cancer treatment, cat scans, nuclear reactions
Radio waves
Microwaves
Infrared
Visible Light
Ultraviolet
x-rays
Gamma
Long wavelength
Short wavelength
Low frequency
High frequency
Low energy
Light and Color Notes
 Visible Light is the only electromagnetic wave humans can see
High energy
Review: Interactions of waves with light
 Diffraction is the bending of waves around barriers or through openings.
 Interference is a wave interaction that happens when two or more waves
overlap
o Constructive: 2 waves build up to a bigger wave
o Destructive : 2 waves cancel each other out or make a smaller wave
 Reflection happens when light waves bounce off an object
o Remember the law of reflection states that a wave will bounce back
at the same angle it hit the barrier!!!
o Flames, light bulbs, and the sun are all light sources.
o Most things around you are not light sources but you can see them
because light from light sources reflect off objects and into your eyes
 Refraction is the bending of a wave as it passes at an angle from one
material to another.
o Refraction of light waves happens because light travels at different
speeds in different mediums
How we see light:
 White light has many different wavelengths and they all bend at different
angles
 Humans see different wavelengths of light as different colors
 Waves with shorter wavelengths bend more than waves with longer
wavelengths which cause the different colors of the rainbow
ROY G BIV Foldable
Long wavelength to short
wavelength
Low frequency to high
frequency
 The color that an object appears to be is determined by the wavelength of
light that reach your eyes.

Light reaches your eyes after being reflected off an object
 When white light strikes a colored object, some colors of light are
absorbed, and some are reflected
o Absorption: The process by which objects take in light energy (eats
it!)
 Only the light that is reflected reaches your eyes and is detected.
o So, the colors of light that are reflected by an object determine the
color you see
o Objects appear to be blue because it reflects blue wavelengths and
absorbs all other wavelengths
o Objects that REFLECT ALL wavelengths of visible light appear white
o Objects that ABSORB ALL wavelengths of visible light appear black