Properties of waves
● Wave is a disturbance that travels through a medium from one point in space to another
● The wavelength of a wave is the distance from a point on one wave to the same point on the next
wave. Usually this is measured from the top of one wave to the top of the next wave
● The amplitude of a wave is its height, measured from the middle of the wave to is top
● The frequency of a wave is the number of waves passing a point per second
● Wave motion
○ Oscillating or vibrating motion in which a point or body moves back and forth along a line about
a fixed central point
● Waves
○ Mechanical waves
■ Longitudinal waves
■ Transverse waves
○ Electromagnetic waves
■ YV, x-rays, infrared, radio waves ,gamma rays, visible light
● Electromagnetic waves
○ Doesn’t need matter to travel
● Mechanical waves
○ Waves that require a medium for the energy to travel
○ E.g water waves, sound waves etc.
● Transverse waves
○ In a transverse waves, the particles vibrate at right angles to the direction of movement of the
wave
○ E.g radio waves, light waves, water waves
● Longitudinal waves
○ The particles vibrate backwards and forwards in the direction that the wave travels
○ Examples - sound, a wave on a spring where the hand moves backwards and forwards
● Reflection
○ When a wave reaches a boundary, it is
■ Partially reflected (bounces off the surface)
■ Partially transmitted (through the surface)
● Rules of reflection
○ Distance of wavelength must be same
○ Frequency stays same
○ Speed stays same
○ Amplitude may change
● Refraction
○ Bending of light waves
● Deep to shallow
○ Angle of incidence greater than 0
○ Wavelength and velocity decreases
○ Frequency unchanged
○ Moves towards normal
● Shallow to deep
○ Angle of incidence = 0
○ Wavelength increases, velocity
increases
○ Frequency increases
○ Moves away from normal
● Why speeds are greater in deep water than shallow
○ It is because as the depth of the water decreases, the amplitude of the wave increases and the
resistance to the propagation of the wave increases
○ The increase in amplitude causes the reduction of the wavelength, it becomes taller and
skinnier. This keeps the frequency of the waves constant, no waves disappear or appear from
nothing
● Wavefronts
○ A wavefront is a line or plane on which the vibrations of every point on it are in phase and are at
the same distance from the source of the wave
● Diffraction
○ When waves encounter obstacles, the bending of waves around the edges of an obstacle is
called diffraction
○ Diffraction occurs when a wave encounters an obstacle or a slit. It is defined as the bending of
light around the corners of an obstacle or aperture
Diffraction can be increased by reducing slit width. When the gap to
the wavelength is equal, maximum diffraction occurs and the waves
spread out greatly. The wave fronts are almost semi-circular
