Download Chapter 4 Many properties of light can be understood using a wave

Chapter 4
Many properties of light can be
understood using a wave model of light.
Vocabulary
Section 4.1
The Nature of Light
Pythagoras
A Greek philosopher who believed
that light beams were made up of
tiny particles.
Microscope
An optical
device used to
magnify
extremely small
objects, such as
microorganisms;
composed of a
combination of
lenses.
Telescope
An optical device
used to magnify
distant objects,
such as stars and
planets;
composed of a
combination of
lenses or lenses
and mirrors.
Section 4.2
Properties of Waves
Wave
A disturbance or movement that
transfers energy through matter or
space, without causing any
permanent displacement.
Crest
The highest part of a wave.
Trough
The lowest part of a wave.
Wavelength
Distance from one wave crest to the
next; length of one unit of a wave
that repeats itself.
Amplitude
The distance between the highest
point (crest) on a wave and the rest
position; also, the distance between
the lowest point (trough) and the
rest position.
Frequency
The number of repetitive motions, or
vibrations, of a wave that occur in a
given amount of time; measured in
cycles per second or Hertz (Hz).
Energy
The capacity to apply force over a
distance.
Force
Anything that
causes a
change in the
motion of an
object; a push
or pull on an
object.
Compression Waves
A wave for which the action making
the wave is back and forth along the
direction in which the wave is
moving.
Transverse Waves
A wave for
which the action
making the
wave is
perpendicular to
the direction in
which the wave
is travelling.
Hertz
Cycles per second; unit used to
measure frequency of a wave.
Medium
The material or substance through
which a wave is moving.
Section 4.3
Properties of Visible Light
Visible Light
A form of
energy that
you can
detect with
your eyes.
Spectrum
The array of colours of light that
result from the separation or
dispersion of white light.
Wave Model of Light
A model in which light is a type of
wave that travels through space and
transfers energy from one place to
another.
Reflection
The process in which light or another
type of wave interacts with a surface
and is sent back from the surface.
Refraction
The changing of
direction or
bending of light or
other type of
wave when
travelling from
one medium to
another medium
having a different
density.
Section 4.4
Light and the
Electromagnetic Spectrum
Radiant Energy
Energy, such as light, that spreads
out from a source in all directions.
Electromagnetic Radiation
A repetitive movement, not of
particles, but of electric and
magnetic energy through space.
Radio Waves
Electromagnetic waves having
wavelengths from a few centimetres
to several kilometres long.
Ultraviolet Waves
Electromagnetic
waves with
wavelengths
between
4 × 10–7 m and
4 × 10–9 m.
X-rays
Electromagnetic waves with very
short wavelengths, between about
3 × 10–9 m and about 1 × 10–12 m.
Microwaves
Electromagnetic waves having
wavelengths between 0.3 cm and 30
cm.
Infrared Waves
Electromagnetic
waves having
wavelengths
between
3 × 10–4 m and
7 × 10–7 m.
Gamma Rays
The portion of the
electromagnetic
spectrum with the
highest energy,
highest frequency,
and lowest
wavelength; result
from nuclear
reactions; used in
cancer therapy.