# Waves notes

WAVES AND SOUND

SUMMARY

Travelling wave characteristics

Waves transfer energy without transporting matter because each part of the medium oscillates on the spot.

The medium is the material that vibrates when a wave passes.

A transverse pulse causes the spring to move at right angles to the direction of motion of the pulse.

A longitudinal pulse causes the spring to move parallel to the direction of motion of the pulse.

A transverse wave is polarized when it vibrates in only one plane.

Longitudinal waves cannot be polarized.

Displacement is the position of a particle in a medium relative to its normal position.

Superposition : When two pulses over lap the total displacement at all points along the medium equals the sum of the individual displacements.

The speed of the particles of a medium is a maximum when their displacement is zero.

The speed of the particles of a medium is zero where the medium has maximum displacement.

The amplitude of a wave is the greatest distance the medium moves from its normal position.

The wavelength of a wave is the distance from any point to the next corresponding point.

The period of a wave is the time it takes to move one wavelength.

The frequency of a wave is the number of waves that pass in one second.

The frequency is the reciprocal of the period.

The speed of a wave equals its frequency times its wavelength.

A displacement/time graph shows the position of one particle in the medium as the wave passes.

A displacement/distance graph shows the position of each particle along the length of the medium.

For a longitudinal wave, a compression occurs when particles are closer than normal and the pressure is higher than normal.

The particles in a compression move in the same direction as the wave.

The particle at the centre of the compression has zero displacement and is moving in the forward direction at the same speed as the wave.

...