Lesson Notes By Weeks and Term v4 - SHS 2
WAVES
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WAVES
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Subject: Physics
Class: SHS 2
Term: 1st Term
Week: 16
Grade code: 2.2.2.LI.3
Strand code: 2
Sub-strand code: 2
Content standard code: 2.2.2.CS.1
Indicator code: 2.2.2.LI.3
Theme: ENERGY
Subtheme: WAVES
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Waves are all around us in Ghana. We experience them when we see ripples on the surface of the Volta River or the sea at Labadi Beach. We hear them as sound from a speaker playing highlife music or the horn of a trotro. We use them every day when we listen to the radio (e.g., Joy FM, Peace FM) or use our mobile phones. This lesson will equip you with the scientific language and mathematical tools to describe these waves accurately. By understanding properties like amplitude, wavelength, and frequency, we can understand how all these different wave phenomena work.
Introduction: Visualising a Wave Imagine you and a friend are holding a long rope. If you shake your end up and down steadily, you create a wave that travels along the rope to your friend. This visual model helps us understand the properties of a transverse wave, where the particles of the medium (the rope) move perpendicular to the direction the wave energy is travelling.
The shape you create is often a smooth, repeating pattern called a sinusoidal wave. Equilibrium Position: The straight, dashed line represents the rope's position when it is still. This is the "zero" or "rest" position. Crest: The highest point of the wave. Trough: The lowest point of the wave.
Now, let's define the key terms used to describe this wave. Amplitude (A) Definition: The amplitude is the maximum displacement or distance moved by a point on the wave from its equilibrium position. Explanation: It is simply how "high" the crest is, or how "low" the trough is, from the middle line. Amplitude is related to the energy of the wave. For a sound wave, a larger amplitude means a louder sound. For a light wave, it means brighter light. Unit: Metres (m).
Example: In the diagram above, if the crest is 0.5 metres above the equilibrium line, the amplitude A = 0.5 m. Wavelength (λ) Definition: The wavelength is the distance between two consecutive corresponding points on a wave. It is the length of one full wave cycle. Explanation: The easiest way to measure this is the distance from one crest to the next crest, or from one trough to the next trough. The symbol for wavelength is the Greek letter lambda (λ). Unit: Metres (m).