PHYSICS FORM 4: TOPIC 1 - WAVES

WAVES

WAVE:- Is a periodic mechanism which transfers energy from one place to another. Some examples of waves include; light waves, sound waves, water waves, radio waves.

COMMON TERMS USED IN WAVES (WAVE PARAMETERS)

1. PERIOD(T): Is the time taken for the wave to repeat itself.

OR

Is the time taken for the wave to complete one cycle.

It is represented by a letter “T”, and its SI-Unit is second(s).

2. AMPLITUDE(A): Is the maximum displacement of the wave from the equilibrium position.

It is representend by the letter “A”, and its SI-Unit is metre(m).

3. CREST AND TROUGH:

a) CREST: Is the maximum point attained by a wave in positive displacement from the

equilibrium position.

b) TROUGH: Is the maximum point attained by a wave in a negative displacement from the

equilibrium position.

4. WAVE LENGTH (λ): Is the distance between two successive crests or trough of a wave.

OR

Is the distance moved by a wave to complete one cycle or oscillation.

It is denoted by the Greek letter called Lambda (λ), and its SI-Unit is metre (m).

5. FREQUENCY (f): Is the number of cycle made per unit time.

It is denoted by a letter f, and its SI-Unit is per second (s-1) or Hertz (Hz).

6.WAVE VELOCITY/SPEED (V): Is the distance travelled by a wave per unit time.

OR

Is the displacement travelled by a wave per unit time

It is denoted by a letter “V”, and its SI-Unit is metre per second (m/s).

TYPES OF WAVES

There are two types of wave namely:-

i) Electromagnetic waves

ii) Mechanical waves

i) ELECTROMAGNETIC WAVES: - These are waves which do not require medium for their

propagation

• Electromagnetic waves are disturbances made up of electric and magnetic fields.

• They travel through vacuum. Visible light is an example of electromagnetic wave.

NOTE: The speed of all electromagnetic waves is 3.0 X108m/s

ii) MECHANICAL WAVES: - These are waves which require material medium for their propagation.

• Mechanical wave is a disturbance which is transported through a medium due to particle-

to-particle interaction.

• Sound wave and water wave are examples of mechanical waves.

• As mechanical waves travel through a medium, the particles that make up the medium are disturbed from their rest or equilibrium positions

TYPES OF MECHANICAL WAVES

i) Transverse waves

ii) Longitudinal waves

i) TRANSVERSE WAVES:- Is the one in which the direction of vibration of particles is perpendicular

to the direction of the travel of the wave motion.

• Water wave is an example of transverse wave, the water particles move up and down

while the waves move in a horizontal direction. That is why a boat moves up and down

while the waves themselves move towards the shore.

ii) LONGITUDINAL WAVE:- Is the one in which the direction of the vibration of particles is parallel to the direction of the travel of the wave motion.

NOTE: In longitudinal waves there is a state in which the vibration of particles is so close

(compression) and the case in which the vibration of particles are spread out or for apart

(rarefactions).

FULL TOPICS