(3.2-3.9) Wave properties

Define transverse wave.

A wave that oscillates perpendicularly to the direction of energy transfer

Define longitudinal wave.

A wave that oscillates in the same direction as energy transfer.

What are the properties of a longitudinal wave?

• have compressions and rarefactions

• parallel to direction of energy transfer

• cannot travel in a vacuum

• can travel through solids, liquids. gases

• changes in density

• changes in pressure

• speed depends on material

  • fastest in a solid

What are the properties of a transverse wave?

• have peaks and troughs

• perpendicular to direction of energy transfer

• can travel in a vacuum (EM)

• can travel through solids + surface of liquids

• constant density

• constant pressure

• speed depends on medium

  • fastest in vacuum

What is a compression?

Parts of a longitudinal wave where the points are close together

What is a rarefaction?

Parts of a longitudinal wave where the points are far apart

What is a peak?

The top of a transverse wave

What is a trough?

The lowest point of a transverse wave

What are examples of longitudinal waves?

Sound waves

Shock waves

What are some examples of transverse waves?

Light + all other electromagnetic waves

Define amplitude.

The max or min displacement from the undisturbed position (the height in m)

Define wavelength.

The distance in m from one point on the wave to the same point on the next wave

• peak to peak

• centre of one compression to the centre of the next

Define frequency.

The number of waves passing a point in a second. (Hz)

Define period.

The time in s taken for a single wave to pass a point.

What is a wavefront?

imaginary planes that cut across waves, linking them at a specific point

What do waves do?

Transfer energy and information without transferring matter.

What is the relationship used to find the speed of a wave?

v = f * λ

speed = freq. * wavelength

What is the formula linking frequency and period?

f = 1/T

What is the Doppler effect?

The apparent change in observed λ and f of a wave

emitted by a moving source

relative to an observer

What does the Doppler effect mean?

As an emitting source moves closer to the observer, the frequency increases.

Why does the Doppler effect occur?

Wave speed is constant

A moving source = wavefronts bunch up in front of it and spread out behind it

All waves can be…

reflected + refracted

What is reflection?

A wave hitting a boundary between two media and not passing through, bouncing off and remaining in the same medium

What is refraction?

A wave passing a boundary between two different transparent media

and undergoing a change in direction