Question

Define amplitude and frequency of the wave.

Answer 1

suppose blue line is the center line, red loop is the crest and the yellow loop is the trough of a wave

Amplitude - the distance from center line to the crest or from the center line to the trough

Frequency - Number of waves passing a particular point in a second or a particular time

P.S. Frequency is of anything is described number of * that thing * done in one second
for eg. frequency of a sound wave is the vibrations per second

Answer 2

The amplitude, a, of a wave is the distance from the centre line (or the still position) to the top of a crest or to the bottom of a trough. Be careful with this quantity - the centre line is not always given in a diagram. Amplitude is measured in metres (m). The greater the amplitude of a wave then the more energy it is carrying

The wavelength, λ, of a wave is the distance from any point on one wave to the same point on the next wave along. (The symbol is a Greek letter, 'lambda'.) To avoid confusion, it is best to measure wavelength from the top of a crest to the top of the next crest, or from the bottom of a trough to the bottom of the next trough. Wavelength is also measured in metres (m) - it is a length after all