Chapters 20-23 Study Guide
What are electromagnetic waves?
What is the Electromagnetic spectrum (EM
spectrum)?
What is the order of the electromagnetic
spectrum starting with the longest wave
length and ending with the shortest wave
length?
Explain how the light waves are different
from one end of the spectrum to the other in
terms of frequency and wavelength.
List one characteristic and example of each
of the 6 parts of the EM spectrum.
Explain the Law of Reflection.
What is the difference between clear
(regular) reflection and diffuse reflection?
What is the difference between absorption
and transmission?
The color of an object depends on the color
of the light it ____________?
What is scattering?
Transverse waves made of self-propagating
magnetic and electric fields. The movement of
charged particles produces electromagnetic waves.
They do not require a medium to move energy. All
electromagnetic waves travel at 300,000 km/s.
the range of electromagnetic waves
Radio and microwaves; infrared; visible light;
ultraviolet; x-rays; gamma rays
The light on the spectrum moves from long
wavelength to short wavelength, from low
frequency to high frequency, and from low energy
to high energy.
R = longest wavelength; communication, cooking
I = all objects emit these rays; warming things
V = what humans see; white light, rainbow
U = shorter wavelength; skin cancer, sterilization
X = even shorter wavelengths; medical diagnosis,
airport security
G = shortest wavelengths of all; radiation
treatments, cancer
the angle of incidence is equal to the angle of
reflection. Be able to label a diagram and measure
both angles
clear - when light is reflected at the same angle
(smooth, shiny surface)
diffuse - when light is reflected in different angles
(rough, dull surface)
Transmission is the passing of light through matter
Absorption take in light energy and does not allow
it to transmit. It transfers energy from light waves
to particles of matter; this energy can be changed
into heat.
reflects
(a red book only reflects red light and absorbs the
rest)
Scattering is the absorption and release of light
from matter in all directions. Scattering causes the
sky to be blue.
Translucent objects scatter light.
What material allows all light to be
transmitted and no light to be absorbed?
Give an example.
What material allows some light to be
transmitted and absorbed? Give an example.
Transparent – clear glass filled with water
Translucent – tissue paper or white paper
Opaque – black paper or rocks
What material allows no light to be
transmitted and all light to be absorbed?
Give an example.
What are the primary colors of light?
What are the primary pigments?
Primary colors: Red, green and blue will combine
to produce white light.
Pigments: yellow, cyan and magenta. Pigments
absorb some light and reflects others.
Black
What color do you have if all colors are
absorbed and no light is reflected?
What is an object that produces light?
What is an object that reflects light?
Luminous
Non-luminous
List the 4 properties of light.
Light travels in a straight line.
Light travels much faster than sound.
We see things because they reflect light into our
eyes.
Shadows are formed when light is blocked by an
object.
How does the electromagnetic spectrum
change from one end to the other?
Wavelengths are long and frequency is low at the
radio waves end of the electromagnetic spectrum
and become short wavelengths and high frequency
at the gamma rays end of the spectrum.
How do convex mirrors and lenses curve?
How do concave mirrors and lenses curve?
Which lens or mirror diverges? Which
converges light into a single point?
curve out
curve in
Convex lenses & concave mirrors – converge light
(bends it in)
Concave lenses & convex mirrors – diverges light
(bends it out)
A concave mirror
Light rays refract inward because of the lenses so
the focus is on the back of the eye (retina) and a
person can see clearly.
What type of mirror magnifies?
How does refraction through lenses help a
person who wears glasses to see?
(how do the light rays bend)
What are the 5 steps in how light is
produced?
Explain what a photon is.
1.Electrons move around the nucleus.
2.Electrons absorb energy and jump to a new
position.
3.This new position is unstable, so electron returns
to its original position.
4.Electrons release a photon when it jumps back to
its original position.
5.A stream of photons from the movement of
electrons is thought to be EM waves.
A photon is a particle-like packet of radiant or light
energy.
What do waves transfer?
Transfer energy from one place to another
What is interference?
Wave interaction that occurs when 2 or more waves
overlap
What is the crest of one wave overlapping the
crest of another wave producing a larger
wave? Give an example.
What is the crest of one wave overlapping the
trough of another wave producing a smaller
wave? Give an example.
What is wave interaction in which waves
bend around barriers?
Give an example.
What is the bending of a wave as it passes at
an angle from one medium to another?
Constructive interference
Loud sound, bright light
What is when a wave bounces back after
striking a barrier?
Reflection
What is the section of a wave where matter
being squeezed together?
What is the section of a wave where the
particles are less crowded?
What type of wave is sound and how is sound
produced?
What is the difference between a standing
wave and a propagating wave?
Give an example of each.
In what medium is sound fastest? Slowest?
How frequency is perceived and how high or
low sound is
Destructive interference
Soft sound, dim light
Diffraction hearing sound around a corner
Refraction-rainbow, pencil in water
Compressions (longitudinal waves only)
Rarefactions
Sound is a longitudinal, mechanical wave (requires
a medium). Sound is produced by vibrating matter.
Standing wave does not move.
Propagating wave moves.
Guitar string and sound in air
Fastest in solids like steel / slowest in gases like air;
Increases with temperature
Pitch
If you have a low frequency, what type of
pitch will there be?
High frequency has what pitch?
If you have high amplitude, what type of
sound will you have?
Low pitch
High pitch
The larger the amplitude, the louder the sound (in
decibels)
What is the apparent change in frequency of
a wave created by a moving object?
Doppler Effect
An approaching object like a car will have
-Short wavelength and have high frequency = high
what type of wavelength and pitch? When it pitch
moves away what wavelength and pitch will
-Long wavelength and low frequency = low pitch
it have?
What is the reflection of sound called?
What adaptation have some animals
Echo
developed where they reflect sound waves to Echolocation
detect objects and locate food?
Study your previous wave and sound quiz.
Be able to identify and label both types of waves.
Any question on that quiz may (and probably will be) on the test.
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