**N4/5 Waves**

**Waves**

A wave transfers energy from one point to another.

There are 2 types of waves: TRANSVERSE & LONGITUDINAL.

Light, Radio and Water waves are transverse. Sound waves are longitudinal.

In transverse waves the particles move at 90° to the wave direction and in longitudinal waves the particles move in the same direction of the wave.

**Diffraction**

Diffraction is the bending of waves around obstacles.

Longer wavelengths diffract more than shorter wavelengths.

More Diffraction from smaller gaps.

**Sound**

Sound levels are measured in decibels (dB).

Regular exposure to noise levels above 85-90 dB can cause damage to hearing.

90 dB and above are examples of noise pollution.

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**Ultrasound**

Ultrasounds are sounds above the range of human hearing (20 Hz - 20,000 Hz)

An ultrasound scanner can be used to examine the inside of a patient. A signal is sent out and then reflected back to the scanner.

**Reflection**

Law of reflection: The angle that the incoming ray makes with a flat mirror is always the same as the angle it is reflected at.

The normal is an imaginary line that we draw at 90° to the object.

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