In the above animation, five points on the wave are considered for the explanation. The fully interactive applet is given below for you to practise. The phase of a point implies its direction of vibration on a wave. For example, both points A and E vibrate exactly the same way are said to be in phase: when A goes up so does B; the phase difference is either 0 0 or 360 0 . If you consider the motion of points A and C, on the other hand, when A goes down C goes up or vice versa. Therefore, A and C are said to be out of phase; the phase difference is 180 0 . That means the phase difference between two points on a wave - or two waves for that matter - can take any value between 0 0 and 360 0 . The phase difference between points A and B, for instance, is 90 0 . From the above examples, it is clear there is a connection between the path difference between two points - or two waves - and phase difference. It is as follows: Phase difference = (path difference / wavelength) x 360 φ = x
Waves A wave carries energy from a point to another point in a medium / vacuum without the movement of the particles along with it. In the above animation, the wave moves from the left to the right; the particles, however, just vibrate vertically without moving along with the wave. Transverse Waves If the direction of the wave is perpendicular to the vibration of particles, it is called a transverse wave. E.g. Water waves, radio waves, microwaves Amplitude The maximum displacement of a particle in a wave is called amplitude. Intensity / loudness The intensity / loudness of a wave is proportional to the square of the amplitude. The greater the amplitude, the greater the intensity / loudness. Amplifier This is what an amplifier does: it increases the amplitude of an input signal, which in turn leads to the increased loudness or intensity. Frequency - f The number of cycles of a wave that passes through a point in a unit time is called frequency. Wavelength - λ The distance between
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