Year 9 Week 27 Quiz: April 11, 2015
Vocabulary: (note units where applicable)
Frequency: The number of waves that pass a point in a certain amount of time. Measured in Hertz (Hz)
[SI Unit]
Hert (Hz): 1 Hert = 1 wave per second
Period: The time it takes for one wave to pass a point is called a period. Periods can be measured in
any unit of time. If the period of a wave is measured in seconds then the frequency of the wave
is equal to the reciprocal of the period:
Frequency
1

1
Period
Wavelength: The length of one wave oscillation. Measured from one point on a wave to the exact
point on the next wave. Measured in meters (cm [10-2], mm [10-3], nm [10-9]).
Note: Wavelength and frequency are inversely related. This means when frequency increases,
wavelength decreases (or vice versa)
Frequency
1

1
Wavelength
Amplitude: Displacement of the medium when the wave moves through it. (How far the medium
moves from its equilibrium point). Depends on the amount of energy transferred by the wave.
Speed: How fast the wave moves. Depends on density of medium. Related to the frequency and
wavelength of the wave.
Symbols:
λ = Greek letter lambda it represents the wavelength in meters
ν = Green letter ‘nu’ it represents the frequency can also be represented by
italicized f
c = italicized ‘c’ is speed
Example problem: The wavelength of green light is 522nm. If the speed of light is 3.0 x 10 8 m s -1,
what is the frequency of green light radiation?
Red
Violet
Deep (far) Red
Blue
Also, remember how red or blue shift not only relates to direction but the speed of motion of an object
(see below).
Slower
More red = Faster
And we talked about retrograde motion and
what support toward the heliocentric
model of the Universe its observation
provides.
We Also talked about the fact that atoms have energy levels which electrons move up and down, and
depending on that motion variable light waves of different frequencies are emitted, and this
leads to the emission spectra of various elements
We also talked about refraction of light
through a prism or any translucent object of a
variable thickness medium, and that this
refraction is also principally how lenses work.
.
Read in your book Chapters:




2.2 pages 118-199,
3.1 page 136-137,
3.2 page 138-139,
3.3 pg 140-141
And do summary questions