ADDITIONAL SCIENCE FORM 5CHAPTER 4: VIBRATION AND

WAVE PROPAGATION

4.1 VIBRATION AND WAVE

A vibrating system is a system which oscillates uniformly within its equilibrium position. The vibrating system produces disturbances in the form of waves.

4.1 VIBRATION AND WAVE

A simple pendulum is an example of a vibrating system

4.1 VIBRATION AND WAVE

Equilibrium position

One complete oscillation in a simple pendulum

4.1 VIBRATION AND WAVE

Equilibrium position

Amplitude (a) is the maximum displacement

of the wave from the equilibrium position

O

Period (T) is the time required for a complete wave to pass

through a given point. The unit is in second (s)

Wavelength (λ) is the minimum

distance between two points that have the same

displacement. The unit is in metres

(m)

Frequency (f) is the number of complete

wave that passes through a given

point in one second. The unit is in hertz

(Hz)

4.1 VIBRATION AND WAVE

The natural frequency of a vibrating system is the frequency the system

moves on its own. If a forced frequency from another vibrating system is applied on a vibrating system, it produces a forced vibration. Resonance occur when the natural frequencies of two objects are the same.

4.1 VIBRATION AND WAVE

Resonance in tuning forks Two tuning forks with the same natural frequency are set

close together

One is set into vibration and then stopped after a few seconds while the other tuning fork is still vibrating

The sound waves of the first tuning fork causes the second fork to vibrate

Large vibration (big amplitude) can be produced when the forced frequency of the second tuning fork is equal to its

natural frequency

4.1 VIBRATION AND WAVE

Video on resonance:

4.1 VIBRATION AND WAVE

Video on resonance:

4.1 VIBRATION AND WAVE

There are many things in our surroundings that operate on the principle of resonance. The natural frequency of electric

currents in a circuit may be tuned to that of an incoming radio signal, which is then

amplified and converted into sound.

4.2 THE PROPAGATION OF WAVE

The propagation of wave is also the propagation of energy.

Types of waves

Transverse wave Longitudinal wave

4.2 THE PROPAGATION OF WAVE

Video on waves:

4.2 THE PROPAGATION OF WAVE

Production of sound wave

4.2 THE PROPAGATION OF WAVE

Transverse wave Longitudinal wave The direction of wave propagation is perpendicular to the direction of

the particles

The direction of wave propagation is the same as the direction of

particles Able to propagate through vacuum Unable to propagate through

vacuum. It needs a medium to travel

Able to transfer energy Able to transfer energyExample: water waves Example: sound waves

4.2 THE PROPAGATION OF WAVE

The propagation velocity (v) of a wave is the velocity of the energy transfer and is given by the frequency (f) travelled by the wave multiplied by the wavelength (λ). v = f λ

where v is velocity in ms-1

f is frequency in Hzλ is wavelength is m

4.2 THE PROPAGATION OF WAVE

Example 1:Find the velocity of a wave with a wavelength 2.5 m and frequency 44 Hz. Solutionv = f λ = 44 x 2.5 = 110 ms-1

4.2 THE PROPAGATION OF WAVE

Example 2: The FM band of a radio has a frequency of 100 MHz. Find the wavelength of an FM wave if the velocity of the electromagneticwave is 3 x 108 ms-1.

4.2 THE PROPAGATION OF WAVE

Solution λ = v f = _3 x 108

100 x 106

= 3 m