What is a wave?
A wave is a disturbance that propagates through space and time.
Waves travel and transfer energy from one point to another often with no permanent displacement of the particles of the medium.
Wave Motion:
Wave motion in a medium is due to the generated disturbance which causes the constituents particles to repeat it's to and fro motion about its mean position in equal interval of time and this disturbance is passed over from one end of the medium to the other.
Simple Harmonic Motion:
Simple harmonic motion is a kind of vibratory motion in which acceleration of the body is directly proportional to the displacement from equilibrium position and always directed towards the equilibrium position.
It repeats itself at standard intervals in a specific manner.
a – x
f/m -x
f/m=-k/m (x) since k/m is a constant
f=-kx here is k is called spring constant
the ratio of the external force acting on a spring to the increase in its length is called spring constant. its unit is N/m
Simple Pendulum:
A pendulum is a weight suspended from a pivot so that it can swing freely. Acceleration of the bob is always directed towards the mean position. Speed of the bob is maximum at mean position while minimum at the extreme positions.
[Click on the image to see it moving]
Mechanical waves:
The kind of waves which require a medium for their propagation are called mechanical waves
Transverse waves:
The waves in which the particles of medium vibrate perpendicular to the direction of propagation of the wave.
If you anchor one end of a ribbon or string and hold the other end in your hand, you can create transverse waves by moving your hand up-and-down. Notice though, that you can also launch waves by moving your hand side-to-side.
Compressional or longitudinal waves:
[Click on the image]
They type of waves in which the direction of the vibratory motion of the particles of medium is parallel to the direction of propagation of the wave.
In longitudinal waves the displacement of the medium is parallel to the propagation of the wave. A wave in a "slinky" is a good visualization. Sound waves in air are longitudinal waves
Ripple tank:
Ripple tank is a shallow glass tank of water used to demonstrate the basic types of waves.
Reflection:
Reflection is a change in direction of a wavefront at an interface between two different media so that wavefront returns into the media through which it is originated.
Refraction:
Refraction of waves involves a change in the direction of waves as they pass from one medium to another. Refraction, or the bending of the path of the waves, is accompanied by a change in speed and wavelength of the waves. Angle of incidence (angle between incident ray and normal) for which angle of refraction (angle between refracted ray and normal) is ninety degree, is called critical angle. If angle of incidence exceeds critical angle, then the refracted ray comes back into the first medium and hence its called total internal reflection.
Diffraction:
diffraction involves a change in direction of waves as they pass through an opening or around a barrier in their path. Water waves have the ability to travel around corners, around obstacles and through openings. This ability is most obvious for water waves with longer wavelengths
Interference:
[Click on the image]
Interference is addition of two or more waves that result into a new wave pattern.
If identical waves pass through a medium in such a way that crest of one wave falls on the crest of other and trough of one on trough of other, then resultant displacement may get double the displacement of individual wave. Such interference is called constructive interference
And if identical waves pass through a medium in such
a way that crest of one falls upon the trough of other, then they cancel the effect of each other and as a result the surface of medium remains undisturbed. Such interference is called destructive interference.
Stationary waves:
When two waves of same frequency moving in opposite direction superimpose we have stationary waves. The amplitude in such waves is different on different sections. The sections where amplitude is zero are called Anti-nodes (denoted by AN in the fig) and the sections where amplitude is maximum are called Nodes( denoted by N in the fig).
wavelength of such waves is twice the distance between two successive nodes or anti-nodes.
