Water Waves------Water waves are an example of waves that involve a combination of both longitudinal and transverse motions. (see fig.5)As a wave travels through the waver, the particles travel in clockwise circles. The radius of the circles decreases as the depth into the water increases. The movie below(see fig. 6) shows a water wave travelling from left to right in a region where the depth of the water is greater than the wavelength of the waves. I have identified two particles in yellow to show that each particle indeed travels in a clockwise circle as the wave passes.

figure. 7

figure. 6

Diffraction-----Diffraction is the bending of waves round corner (see fig.7). Diffraction waves have unchanged frequency and wavelength. The amount of diffraction is great when the wavelength is about the same size as the gap or the obstacle.

Interference------When two pulses traveling on a string meet each other (see fig.8), the amplitudes of the pulses are added together to produce the shape of the resulting pulse. If the pulses are identical but travel on opposite sides of the string, then the sum of the amplitudes is zero and the string will appear flat for one instant (A). This is called destructive interference. When the two identical pulses travel on the same side of the string, then the sum of the amplitudes is double the amplitude of a single pulse when the pulses are together(B). This is called constructive interference.

figure 8

Made by 5B's students!