3.1 General wave properties
Wave: A disturbance that repeats regularly in space and time and that is transmitted progressively from one place to the next with no actual transport of matter. A disturbance, oscillation, or vibration propagated (moving through) a medium or space.
Examples: Sound waves, Water waves, Light waves
• Demonstrate understanding that waves transfer energy without transferring matter
• Describe what is meant by wave motion as illustrated by vibration in ropes and springs and by experiments using water waves

Simple harmonic motion: The back-and-forth vibratory motion of a swinging pendulum.
• Give the meaning of speed, frequency, wavelength and amplitude
• Distinguish between transverse and longitudinal waves and give suitable examples


Transverse wave:
Oscillation is perpendicular to direction energytravels.
A wave with vibration at right angles to the direction the wave is traveling.

Longitudinal wave:
Oscillation is parallel to direction energy travels.
A wave in which the vibration is in the same direction as that in which the wave is traveling, rather than at right angles to it.

Crest / Peak: One of the places in a wave where the wave is the highest or the disturbance is the greatest.

Trough: One of the places in a wave where the wave is the lowestor the disturbance is greatest in the opposite direction from a crest.

Compressions: The most dense part of a longitudinal wave.

Rarefactions: The least dense part of a longitudinal wave.

Wavelength: Distance along the wave to the next particle making the same oscillation.
The distance from the crest of a wave to the following crest, or equivalently, the distance between successive identical parts of the wave.

Amplitude: Maximum displacement of a particle.
The distance from the midpoint to the maximum (crest of a wave), or equivalently, from the midpoint to the minimum (trough).

Displacement: Distance of a particle in the wave from its rest position.

Period: Timetaken for one oscillation. The time required to complete a single cycle.

Frequency: Number of oscillations in one second .

Hertz: The SI unit of frequency . One hertz (Hz) is one cycle per second.

Wave speed: The speed with which the energy of the wave travels.

Wavefronts: A line of surface which joins the peaks of a transverse wave or the compressions of a longitudinal wave.

Oscillation: Regular variation in magnitude or position around a central point.
Vibration: The back-and-forth vibratory motion of a swinging pendulum. An oscillation, or repeating back-and-forth motion, about an equilibrium position.
Oscilloscope: Apparatus which represents oscillations by a trace on a screen
Periodic motion: Repetitive motion in regular interval.
Sine curve: A curve whose shape represents the crests and troughs of a wave, as traced out by a swinging pendulum that drops a trail of sand over a moving conveyor belt.
Medium: The intervening substance through which energy is conveyed
Propagate: Move through
Pitch and loudness: Properties of a sound wave which are determined by frequency and amplitude.
Phase: The angle with the respect to the X axis.
A curve whose shape represents the crests and troughs of a wave, as traced out by a swinging pendulum that drops a trail of sand over a moving conveyor belt.

In Phase:
Term applied to two or more waves whose crests (and troughs) arrive at a place at the same time, so that their effects reinforce each other.

Out of Phase:
Term applied to two waves for which the crest of one wave arrives at a point at the same time that a trough of the second wave arrives. Their effects cancel each other.

Test yourself :
State one similarity and one difference between transverse waves and longitudinal waves. Give one real life example of each.

02 wave notes.doc


• Use the term wavefront
WAVEFRONT: A line of surface which joins all points which have the same displacement at the same moment (they are all in phase).
RAY: A line at right angles to the wavefronts which shows the direction of energy travel of the wave.
• Describe the use of water waves to show:
– reflection at a plane surface
– refraction due to a change of speed
– diffraction produced by wide and narrow gaps

• Describe the use of water waves to demonstrate reflection, refraction and diffraction
• Describe how wavelength and gap size affects diffraction through a gap
• Describe how wavelength affects diffraction at an edge

02 link v, f & L-1.doc
06 water waves.doc
Diffraction: Waves spread out after an object of opening with a size similar to the wavelength of the wave.

Reflection and refraction of Waves from physics.usask.ca

• Recall and use the equation v = f λ
• Interpret reflection, refraction and diffraction using wave theory
04 wave equation.doc

( 1.) Using letters for short write down all the information given in the question.
( 2.) Change all the numbers into the basic SI units.
( 3.) Pick an equation that might be useful.
( 4.) If you need to re-arrange it using the formula triangle.
( 5.) Put in the numbers from part ( 1.)
( 6.) Calculator.
( 7.) Show the final units.
( 8.) Check the answer is sensible.
( 9.) Remember, you always get marks for showing your working out !

Speed of light: All EM waves travel at 300 million m/s in a vacuum
Example 1)
What is the speed of a sound wave if it has a frequency of 110 Hz and a wavelength of 3m ?

Frequency f =
Wavelength λ =
Speed v = ?

Example 2)
If the speed of sound in air is 330 m /s and a tuning fork produces a wave with a frequency of 165 Hz what is it’s wavelength ?

Frequency f =
Speed v =
Wavelength λ = ?

Example 3)
If a water wave moves at 25 cm / s and it’s crests are 50 cm apart what is it’s frequency ?

Speed v =
Wavelength λ =
Frequency f =

Example 4)
A sound wave has a frequency of 384Hz and a wavelength of 0.86m. Calculate its speed in m/s.

Example 5)
Another sound wave has a frequeny of 38400 Hz. Would you be able to hear this sound wave? Explain your answer.

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