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Effects on Sound waves

Longitudinal Waves

With the compression and rarefaction occuring simultaneously, it creates a sound wave.

The sound waves travel parallel to the direction of the sound and causes the sound to be carried away.

Names of used in a wave graph

Speed

V; distance moved by one wave in one second

V = fλ

V = λ/T

Period

T; time taken to generate one complete wave. Also the time taken for any point to move 1 wavelength away.

T=f^-1

Frequency

f; number of point passing through a point per second. Unit of frequency hertz (Hz).

Equivalent to the number of complete waves generated per second.

Wavelength

λ; distance between two successive crest or trough points on successive waves.

Amplitude

a; maximum dissplacement from rest (centre of the graph) determines how high the crest is and how low the trough is.

Trough

Negative amplitude; lowest point in the graph/wave.

Crest

Positive amplitude; highest point in the graph/wave.

Wave front

The line that joins all the wave or all identical points on a wave.

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Wave Terms

Main topic

Graphical Representation of waves

Displacement-Time Graph

Displacement-Position Graph

Subtopic

Sounds

Propagation of Sound

Rarefaction

when a preceedding compression left a decompression wave in it's wake and causes a rarefaction to occur.

This causes the air particles to be pulled apart.

Compression

When the a vibration in the air causes the air to be pressed together

This causes the air particles to be pressed together.

Electromagnetic Waves

Types of Electromagnetic Waves

Uses of Gamma Rays

1. Kill cancer cells.

2. kill harmful bacteria in food.

3. Sterilise surgical instruments.

Uses of X-ray

1. Look into a person's body to discover their illnesses or injuries.

2. Check the contains of luggages in immigration offices and airports.

Uses of Ultraviolet Ray

1. Detecting forged bank notes by fluorescence.

2. Fluorescent lights.

Uses of Visible Light

1. Enabling us to see.

Uses of Infrared

1. Optical fibre.

2. Burglar alarms.

3. Remote controls for television sets and DVD player.

Uses of Microwaves

1. Transmit signals such as mobile phone calls.

2. Heat up food particles.

Uses of Radio Waves

Transmit television and radio programmes.

Characteristics of Electromagnetic Waves

4) They obey the wave equation v=fλ

3) All show waves properties like refraction and reflection

2) They are transverse waves

1) Can pass through vaccum

Effects of Electromagnetic Waves

Damage to living cells and tissues

Gamma ray is ionising radiation

It is used to treat tumour cells. However it could damage the surrounding cells and tissues which absorb the rays

Ionising

Ionisation is the process of ion formation

Ultra-violet rays are highly energetic

Able to ionise atoms which can be harmful to living tissues

Under excessive expore to UV rays can cause sunburn and skin cancer

Heating

When water absorbs micorwaves, they are warmed up

The burning of coal gives out infrared radiation as heat to the surrounding