Waves

Two types of waves

Electromagnetic and mechanical

Mechanical waves

They must travel through a medium. Example, sound waves

Electromagnetic waves

They do not need a medium to travel. Example, light waves

Travelling wave

It is a disturbance that travels out from the source producing it transferring energy from the source to other places through which it passes without transferring matter

Transverse wave

It is wave where the direction of vibration is perpendicular to the direction in which it travels. E.G. water waves

Longitudinal waves

It is a wave where the direction of vibration is parallel to the direction of travel. E.G. Sound waves

Energy carried by a wave

The energy is directly proportional to the amplitude²

Reflection of waves

It is the bouncing of waves off an obstacle in their path

Refraction of waves

It is the changing of direction of waves when it enters a region where its speed changes

Diffraction

It is the sideways spreading of waves into a region beyond a gap or around an obstacle

Principle of superposition of waves

It occurs when two waves from two sources meet a new wave is produced. The displacement produced at any point by this wave is the algebraic sum of the displacements that each wave would produce on its each

Constructive interference

It occurs when waves from two sources meet and the amplitude of the resulting wave is greater than of the amplitude of each of the individual waves

Destructive interference

It occurs when two waves from two sources meet and the amplitude of the resulting wave is less than the amplitude of the amplitude of each of the individual waves

Interference pattern

It occurs when waves from two (or more) sources meet

Polarised wave

It occurs if the vibrations of a transverse wave are confined to one plane only

Stationary waves

It occurs when two periodic travelling waves of the same frequency and amplitude but moving in opposite directions they interfere with each other

Doppler effect

It is the apparent change in frequency of waves due to the motion of the source or the observer