## March 30, 2011

### 3.4 Waves Transfer Energy, not Matter

The easiest way to understand this is through a diagram...

If you're still confused:

1. Imagine holding a rope between you and a friend (or a teacher if you have no friends)
2. Shake the rope up and down to create a transverse wave
3. Kinetic energy is sent through the wave to your friend, you know this because your friend will feel the kinetic energy.
4. But the matter (the Rope) hasn't moved, because if it had your friend would end up with a big pile of rope in their arms, and you'd be standing there with your hands empty looking rather stupid.... @_@

### 3.3 Amplitude, Frequency, Wavelength, Period.

Amplitude (a) = The maximum displacement of a wave. Measured from the Equilibrium to the Peak
Frequency (f) = How many cycles of the wave occur per second. Measured in Hertz (Hz).
Wavelength (λ) = The distance between the peak of a wave and the next peak.
Period (T) = The time taken for one complete cycle of a wave.

### 3.2 Longitudinal and Transverse Waves

Longitudinal Wave:
When the displacement of the wave is the same as the direction of flow of energy of the wave
Examples: Spring, Sound

Transverse:
When the displacement of a wave is perpendicular to the direction of the flow of energy of the wave
Examples: Radio, Microwaves, Infrared, Light, Ultraviolet X-rays, Gamma rays, Water, Rope, Spring

### 3.1 Important Units

Degree (°) - Measurement of Angles
Hertz (Hz) - Frequency, How many cycles of the wave occur per second
Metre (m) - Unit of Length

Metre/second (m/s) - A Unit of Speed
Second (s) - Measurement of Time.