New Chapter:Waves

YouTube - Water bubble in Space (zero gravity)

Waves

Waves can transfer energy and with or without particles.

There are two types:

Longitudinal and Transverse

Longitudinal waves

Longitudinal waves have oscillations parallel (in the

same direction) to the direction of

motion

LO: Understand the similarities and differences between types of waves

Longitudinal waves show areas of compression and rarefaction. Examples of longitudinal waves are sound and the primary waves produced by an earthquake

Modelling waves

The wave travels away from the source. The direction of the wave is parallel to the movement of the source.In a longitudinal wave, the coils do not travel horizontally, each coil of the Slinky just vibrates left and right.

LO: Understand the similarities and differences between types of waves

source movesleft and right

coils vibrateleft and right

direction of wave

Transverse waves

Transverse waves have oscillations

perpendicular (at 90°) to the direction

of motion

LO: Understand the similarities and differences between types of waves

Examples of transverse waves are light, water waves and the secondary waves produced by an Earthquake.

Modelling waves

The wave travels away from the source. The direction of the wave is at right angles to the movement of the source.In a transverse wave, the coils do not travel horizontally, each coil of the Slinky just vibrates up and down.

LO: Understand the similarities and differences between types of waves

source movesup and down

direction of wave

coils vibrateup and down

Transverse Wave terminology

Draw the example wave in your book and try and label the amplitude and wavelength.

LO: Understand the similarities and differences between types of waves

Wave terminologyThere are certain definitions regarding waves that you are required to know:•Wavelength – the distance from peak to peak/trough to trough on a wave•Frequency – the number of waves per second. This is measured in hertz (Hz)•Amplitude – The height of a wave above the zero line

LO: Understand the similarities and differences between types of waves

The Wave Equation

V = speed of wave (m/s)

f = frequency of wave (Hz)

λ = wavelength (m)

v = fλv

λf x

Wave equation questions

vλf x

1) A water wave has a frequency of 2Hz and a wavelength of 0.3m. How fast is it moving?

2) A water wave travels through a pond with a speed of 1m/s and a frequency of 5Hz. What is the wavelength of the waves?

3) The speed of sound is 330m/s (in air). When Dave hears this sound his ear vibrates 660 times a second. What was the wavelength of the sound?

4) Purple light has a wavelength of around 6x10-7m and a frequency of 5x1014Hz. What is the speed of purple light?

Wave equation questions

0.2m

0.5m

0.6m/s

3x108m/s