# Waves

Mechanical waves need a substance to vibrate.

Electromagnetic waves vibrate space and do not need a substance to travel through.

Longitudinal waves have vibration parallel to direction.

Transverse waves have vibration perpendicular to direction.

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• Created by: Emily
• Created on: 05-11-12 20:08

## Waves in general.

Mechanical waves need a substance to travel through. Electromagnetic waves do not need a substance to travel through. Longitudional waves have vibration parallel to direction. Transverse waves have vibration perpendicular to direction. Transverse waves can be polarised, this means that they only work in one plane.

Displacement is the distance and direction from the equilibrium position. The amplitude is the maximum displacement. Wave speed = wavelength x frequency. Phase difference is how one point on a wave lags behind another point on a wave. The equation is 2piD/wavelength.

Reflection is where waves change direction.

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## General

Frequency is how often something happens. It is rate quantaty. Cycles/seconds.

Period is the time it takes for something to happen. It is a time quantity. Seconds/cycle.

Waves travel through tighter ropes at higher speeds.

Amplitude does not affect wave speed.

Wavelength does not affect wave speed.

Speed = wavelength / period.

Speed = wavelength x frequency.

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## With two open ends

Waves in

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Nodes

Antinodes

#### Relationship

1 1/2 1 2 Wavelength = (2/1)*L 2 1 or 2/2 2 3 Wavelength = (2/2)*L 3 3/2 3 4 Wavelength = (2/3)*L 4 2 or 4/2 4 5 Wavelength = (2/4)*L 5 5/2 5 6 Wavelength = (2/5)*L

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