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P5 Waves in matter - Coggle Diagram
P5 Waves in matter
Basics
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EG Sound, Electromagnetic, Mechanical
Longitudinal waves. Direction of vibration same as direction of travel. Compressions, rarefactions
Transverse waves. Direction of vibrations perpendicular to distance of travel. Peaks, Troughs
Amplitude. Distance from the middle to the crest/trough of a wave. Symbol = Alpha ( Α). Units = metres or volts (eave dependant)
Wavelength. Distance from a point on one wave to the same point on the next wave. Symbol = Lambda (λ). Units = metres (m)
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Behaviour
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Velocity of ripples calculated with flashing light + ruler. Waves generated by motor. Calculate number of waves passing a point and divide it by time taken. eg 24 waves in 10 secs = 2.4 hz. wavelength measured with ruler from projection on base (caused by light)
Velocity of sound. D=VT. Distance between wall and person X 2 / Time taken for echo to come back from wall. Alternatively use oscilloscope and 2 microphones to measure time between distance. Sound = longtitudinal
Across boundary. Travelling from 1 medium to another can change velocity. REFRACTION. Sound wave moves away at 90° angle to surface (NORMAL) wavelength increases. Frequency remains same
At boundary. 3 things can happen. Sound can be. •Reflected as echo. •Transmitted (maybe refracted) •Absorbed. What happens depends on density either side of the boundary
Ultrasound. sound of frequency > 20000 Hz. HUMANS CANT HEAR. Sound spreads from source. Ultrasound has small wavelength so can be focused into beam. Used to make image of foetus
In Solids. Sounds echo off surroundings. Eventually absorbed. When absorbed, particles vibrate. Get hotter. Diaphragm of microphone can move, absorbs sound and turns into electric signal
Ears. Outer ear directs sound to ear drum. Vibrates. Makes ossicles vibrate. amplify vibration and pass to inner ear through oval window. Only certain range of frequencies heard. Natural frequency is specific to object. If vibration applied at natural frequency, resonance occurs
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