3 Intensity Energy passing through a unit area in unit time. Intensity ~ Square of the amplitudeI ~ A2Intensity ~ 1/d2Where d is distance from source
4 Example 1A health inspector is measuring the intensity of a sound. Near a loudspeaker his meter records an intensity I. This corresponds to an amplitude A of the sound wave. At another position the meter gives an intensity reading of 2 I. What is the corresponding sound wave amplitude?
5 Example 2The intensity I of a sound at a point P is inversely proportional to the square of the distance x of P from the source of the sound. Air molecules at P, a distance r from S, oscillate with amplitude 8.0 μm. Point Q is situated a distance 2r from S. What is the amplitude of oscillation of air molecules at Q?
6 PhaseThe corresponding angular displacement relative to a complete wave of a point on the wave
14 In PhasePhase difference is a multiple of 2п at all points.
15 Out of PhasePhase difference is not a multiple of 2п.
16 Out of PhasePhase difference of п at all points
17 Wave Properties For all waves Reflection Refraction Diffraction Bouncing of waves off a surfaceRefractionChange of wave speed as it passes from one medium to another (from one depth to another)Bending of wavesDiffractionBending of waves around a barrier
18 Wave Properties Question Which wave properties change when light passes from air into glass?A colour and speedB frequency and wavelengthC speed and wavelengthD wavelength and colour
19 Polarisation Oscillation that takes place in one direction. Only true for transverse waves.