Maths, Physics Revision Physicss Maths Physics Physics A Level Physics Home Maths Maths Revision hut Wave properties Previous knowledge λ = ax/D zero order first order first order From previous knowledge we know that waves have a  wavelength and frequency. Two wave are said to be  coherent when they have the same wavelength and frequency and have the  same phase difference (ie in Phase or out by 360o  or  multiples of 360o) Superposition of waves is when two waves pass  through each other Diffraction is when waves pass through a narrow gap  and spread out at the other side. When there are two sets of light waves  spreading out, dark and  light bands are produced  on a screen. This is  Because  when the waves arrive at the screen at the screen in phase there is constructive interference( light bands) and  destructive interference when they arrive out of  phase (dark bands). Young’s double slit experiment use this to work out  the wavelength of a light source Wavelength Vibration in strings

Progressive waves   

The disturbance produced in the medium travels onward, passing from one particle to the next.

The amplitude of each particle is the same but the phase changes continuously,

No particle is permanently at rest. Different particles attain the state of momentary rest at different times

All the particles attain the same maximum velocity when they pass through the zero amplitude position

In longitudinal progressive waves all the parts of the medium undergo similar variation in particle density one after the other. At every point there will be a particle density variation.

There is a flow of energy across  in the direction of the wave


Stationary waves

There is no onward motion of the disturbance as no particle transfers its motion to the next. each particle has its own characteristic vibration

The amplitudes of the  particles are different, ranging from zero at the nodes to maximum at the antinodes. All the particles in a given segment vibrate in phase but in opposite phase relative to the particles in the adjacent segment

The particles at the nodes are permanently at rest but other particles attain their position of momentary rest simultaneously

 All the particles attain their own maximum velocity at the same time when they pass through the zero amplitude position.

In longitudinal stationary waves, the variation in particle   density is different at different points being maximum at the nodes and zero at the antinodes.

Energy is not transported by a standing wave