# Wave Motion And Points On Wave For Cambridge A level And UTME

In this article, I will discuss part of wave (e.g lowest and highest point of waves) and classes of waves**. **A wave allows energy to be transferred from one point to another without any particle of the medium traveling between the two points.

**Classes of Waves**

Wave motion can be classified base on:

- Mode of Propagation

The class of waves under this are

Mechanical wave: this requires a material medium for propagation

Electromagnetic wave: This travels in a vacuum

- Mode of vibration

**The class of waves under this are**:

(i) Longitudinal waves

(ii) Transverse waves

Diagramatic representation of waves

**Points On A Wave**

- Rest position – the undisturbed position of particles when they are not vibrating.
- Peak or Crest – the highest point above the rest position.
- Trough – the lowest point below the rest position.
- Amplitude – the maximum displacement of a point of a wave from its rest position.
- Period (T): it is the time taken for a particle to undergo one complete cycle of oscillation.
- Frequency (f): it is the number of oscillations performed by a particle per unit time.
- Wavelength (λ): it is the distance between any two successive particles that are in phase, e.g. it is the distance between 2 consecutive crests or 2 troughs.
- Wave speed (v): The speed at which the
- Wave front: A line or surface joining points which are at the same state of oscillation, i.e. in phase, e.g. a line joining crest to crest in a wave.
- Displacement : it is the Position of an oscillating particle from its equilibrium position.
- Amplitude: it is the maximum magnitude of the displacement of an oscillating particle from its equilibrium position.

**To deduce V = fλ**

no of cycle = n

time = Tn

distance = **λ**n

substitute all into the velocity = distance/time

Note

F is the frequency and the S.I base unit is Hertz(Hz)

T is the period and the S.I base unit is second(s)

**λ** is the wavelength and the S.I base unit is meter(m)

therefore,

** V = fλ**

Displacement-distance graph and Displacement-time graph

The first graph is a displacement-distance graph. On this graph you can find wavelenght and amplitude

The second graph is a displacement-time graph. On this graph you can find period, frquency and amplitude

The only difference between the two graphs is what you can calculate from it.

Phase difference: this is an amount by which one oscillation leads or lags behiod another. it measures in degree or radian.

Phase difference between waves that are exactly out of phase is π radians or 180 degrees

progressive wave: it is a propagation of energy as a results of vibrations of waves which move energy from one place to another.

Intensity: it is defined as power incident per unit area. The intensity of wave generally decreases as it travels along. The two reasons for this are:

- The wave may spread out
- The wave may be absorbed or scattered

As wave spread out, its amplitude decreases

Read: Longitudinal and Transverse waves

The unit of intensity is

I is the intensity

A is amplitude

f is frequency

r is the distance from the source

Electromagnetic waves travel with the same speed in space

the speed of electromagnetic wave is

Recommended: Solved questions on wave motion

Related Article: Short note on oscillation

**Frequently Asked Questions On Waves**

- What is the lowest point on a wave: The lowest point is the trough
- What is the highest point on a wave – Crest