SPH 3U
8.1, 8.2, 8.3 What is a Wave?
- a wave is a transfer of _________ in the form of a disturbance
usually through a ___________.
- disturbance is transferred, not the medium itself
- electromagnetic radiation (EMR) (Light, ultraviolet, radio) is a
unique example and does not require a medium to travel
Example 1: Bass speaker
- energy transfer (from power plant to speaker to air)
- medium (air)
- disturbance (vibrating movement of speaker causes air molecules
to vibrate back and forth)
Example 2: Drop a pebble into water  water ripples occur in circles
Wave motion
Wave front
- energy transfer from the rock which has speed to the water
- medium the medium is water
- disturbance (raising and lowering of the water level from its rest
position)
- there are two types of waves  transverse (motion of particles
are perpendicular to the motion of the wave) and longitudinal
(motion of the particles are parallel to the motion of the wave)
Transverse Waves
Transverse – the wave travels _______________ to the motion of
the particles in the media and motion of the source
Figure 1: Transverse wave (measure the amplitude, wavelength, state
the # of cycles)
- _________ is a complete sequence of motion that repeats itself.
Sometimes a cycle is called an oscillation, when it involves an
object that vibrates.
- __________ () is the distance from trough to trough or crest
to crest (distance of 1 cycle) measured in meters.
- ______________ is the maximum distance the particle moves
from equilibrium
- any form of electromagnetic radiation is a ___________ wave
Example 1: Determine the number of cycles, amplitude and
wavelength
a)
b)
c)
d)
Example 2: Determine the number of cycles, measure the overall
length and calculate the wavelength
a)
b)
c)
d)
L = ___
L = ___
L = ___
L = ___
e)
L = ___
f)
g)
L = ___
L = ___
Longitudinal Waves
Longitudinal – the wave travels in the ______ direction as the
movement of the particles of the medium (sound wave)
____________ – regions where the particles are close together
____________ – regions where the particles are farther apart
- particles vibrate back and forth about a fixed average position,
but they do not travel from one point to another
-  the disturbance travels, not the medium itself
 sound
Other Definitions:
Pulse – a single disturbance that travels through a medium
Ideal Pulse – the pulse does not
lose any energy while traveling
through the medium
Real Pulse – the pulse loses
energy while traveling through
the medium
time 1: Slinky pulse
time 1: Slinky pulse
time 2:
time 2:
Frequency (f) – total number of
cycles an object completes in a
given amount of time
f=
N
t
UNIT:
1
= Hz
s
where f is the frequency and
N is the number of cycles
Period (T) – time it takes to
complete one cycle (measured in
seconds)
T=
t
N
UNIT: second
where T is the period
How are period and frequency related?
Example 1: A tuning fork produces 12 000 oscillations (vibrations) in
2 minutes. Calculate the frequency and period for the tuning fork.
Example 2: A computer performs 2 500 000 operations in 2
milliseconds. Calculate the clock speed (frequency) of the computer.
Practice Problems:
1) A period of oscillation of a tuning fork is 0.002 seconds (2
milliseconds). In 1 minutes, how many times does the tuning fork
vibrate back and forth?
(Ans: 30 000)
2) The frequency of a yo-yo is 0.75 Hertz. Calculate the period for 1
cycle of motion of the yo-yo.
(Ans: 1.333 s)
3) It takes 4 seconds for FG to run around a track. Calculate the
frequency of FGs motion. (Ans: 0.25 Hz)