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Describing transverse waves and the wave equation. Lesson Objectives: To be able to identify amplitude, wavelength and frequency on a diagram of a transverse wave. To be able to use the equation for wave speed. REMEMBER LAST LESSON….
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Describing transverse waves and the wave equation Lesson Objectives: To be able to identify amplitude, wavelength and frequency on a diagram of a transverse wave. To be able to use the equation for wave speed
REMEMBER LAST LESSON…. • We cannot see light or sound waves so looking at waves moving along a spring can help us learn more about them. • There are 2 main types of waves, they carry a lot of energy from one place to another. • The 2 types are called TRANSVERSE AND LONGITUDINAL waves.
TRANSVERSE WAVES The wave moves at right angles to the disturbance or vibration. LONGITUDINAL WAVES The wave moves along in the same direction as the disturbance or vibration. TRANSVERSE AND LONGITUDINAL
Vibration Wavelength Amplitude Amplitude Wavelength Direction of travel
Vibration Wavelength – Peak to Peak Wavelength – Trough to Trough Direction of travel
Height (m) Frequency – The number of waves per second. If one wave passes in one second it has a frequency of one Hertz or Hz. This is the unit of frequency. 2 1 0 Time (s) 1 2 1 2
How fast do waves travel? • You can work out the speed of a wave if you know….. 1. How many waves pass each second. (the frequency). 2. How long each wave is. (the wavelength)
The wave equation WAVE SPEED = FREQUENCY X WAVELENGTH (m/s) (Hz) (m) Hz is short for HERTZ which is the unit of measurement for frequency.
The wave equation • Example: • Frequency = 165Hz • Wavelength = 2m • What is the wave speed? Wave speed = frequency x wavelength Wave speed = 165Hz x 2m Wave speed = 330m/s
Find the wave speeds…. • 1) Wavelength = 3m, Frequency = 100Hz • 2) Wavelength = 2m, Frequency = 135Hz • 3) Wavelength = 0.5m, Frequency = 200Hz • Remember the 3 step method for equations – YOU MUST DO THIS TO GET FULL EXAM MARKS!!
m/s Wave speed Using your formula triangle means you can work out what equation to use if you need to find wavelength and frequency. Frequency x wavelength m Hz
Further Work • Complete questions................from your text book. • HOMEWORK • How could you measure the speed of water waves. Plan an investigation to show how this can be done.