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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