module 4 chpt 2 energy transfer through waves
TRANSCRIPT
Module 4:Gadgets Work Wonders (II)Chapter 2 Energy Transfer Through Waves
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Chapter 2 Energy Transfer Through Waves2.1 How can a wave be
produced using a rope or a spring to transfer energy?
2.2 How can a wave be described? 2.3 What are the different types of
electromagnetic waves and their uses?
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ObjectivesDescribe what is meant by wave
motion as illustrated by vibrations in ropes and springs
Show understanding that waves transfer energy
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What is a wave?A wave is made up of motion that repeats
itself after a period of time.
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The Kallang Wave is formed when supporters take turn to stand up, raise their hands and sit down. When done with the correct
timing, these motions will form a wave that goes round the stadium in a spectacular manner.
What is a wave?
When a moves his hand up and down continuously, a series of waves are formed and the waves move from left to right.
The kinetic energy from the movement of the hand is transferred through the rope to the fixed end.
The rope is the medium through which the wave travels. If a ribbon is tied at one point of the rope, the ribbon will be
seen moving up and down but not to the right. A wave transfers energy through vibrations without
transferring any part of the medium.© Copyright Star Publishing Pte Ltd
What are the Types of Wave Motion?
A wave motion can be produced using a slinky spring by moving one end up and down while keeping the other end fixed.
Energy is transferred from the vibrating end to the fixed end.
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What are the Types of Wave Motion?
The direction of vibration (up and down) is perpendicular to the direction of the wave (left to right).
Examples of waves that move in this manner are water waves and light waves.
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circular water waves
What are the Types of Wave Motion?
Another type of wave motion can be produced with a slinky spring by moving one end of the spring back and forth while keeping the other end fixed.
In this setup, energy is also transferred from the vibrating end to the fixed end.© Copyright Star Publishing
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Activity Book LinkActivity 2.1Making waves with a Slinky Spring
What are the Types of Wave Motion?
A series of dark and light bands are formed. The dark bands are parts of the coil which are being
compressed and the light bands are parts of the coil which are extended.
The direction of vibration is parallel to the direction of the wave. An example of a wave that moves in this manner is a sound wave.
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Chapter 2 Energy Transfer Through Waves2.1 How can a wave be produced
using a rope or a spring to transfer energy?
2.2 How can a wave be described?
2.3 What are the different types of electromagnetic waves and their uses?
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ObjectivesUnderstand the terms frequency,
wavelength, and the amplitude of a wave
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Terms to describe Waves
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(a) Crests are the highest points of a wave.
(b) Troughs are the lowest points of a wave.
(c) Amplitude is the maximum displacement from the rest position. Its SI unit is the metre.
Terms to describe Waves
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(d) Wavelength (λ) is the distance between twosuccessive crests or two successive troughs. Its SI unit is the metre (m).
(e) Frequency (f) is the number of complete wavesproduced per second. The SI unit is the hertz (Hz).
Activity Book LinkActivity 2.2Observing Water Waves
Amplitude of a wave The amplitude of a
wave is related to the energy which it transfers. The greater the energy a wave transfers, the larger its amplitude.
The wave of a loud sound has a larger amplitude than the wave of a soft sound.
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a wave transferring highenergy has higher amplitude
thana wave transferring low energy€
Chapter 2 Energy Transfer Through Waves2.1 How can a wave be produced
using a rope or a spring to transfer energy?
2.2 How can a wave be described? 2.3 What are the different
types of electromagnetic waves and their uses?
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ObjectivesState how the following types of
waves are used for daily situations: (i) radio waves (ii) microwaves (iii) infrared (iv) light (v) ultraviolet (vi) X-rays and (vii) gamma waves
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Electromagnetic Waves Electromagnetic waves consist of gamma rays, X-
rays, ultraviolet, infrared, visible light, microwaves and radio waves.
These waves form the electromagnetic spectrum.
In the EM spectrum, the EM waves are arranged inthe order of frequency or wavelength:
(a) Radio waves have the longest wavelengths andthe lowest frequencies.
(b) Gamma rays (γ-rays) have the shortest wavelengths and the highest frequencies.
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The electromagnetic spectrum
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Uses of Radio Waves
Radio waves are the EM waves that transfer music from the radio station to your radio set.
Besides radio broadcasting, radio waves are also used for TV broadcasting, radar and global positioning systems (GPS).
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radio waves are used inis radio broadcasting global positioning systems
use radio waves
Uses of Radio Waves
Radio waves have also brought us many conveniences by making it possible to go wireless.
The EZ-Link fare card for taking public transportand the Electronic Road Pricing (ERP) gantriesboth use radio wave technology.
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EZ-Link fare card
ERP gantries
Uses of Microwaves
In a microwave oven, the microwaves cause the water particles in food to vibrate, creating friction which heats up the food in a short time.
Besides cooking, microwaves are also used in mobile phone and satellite communication.
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microwave oven TV remote control unitMobile phones transmit and receive information through
microwaves
Uses of Infrared WavesRemote control units use
infrared waves to transmit information to the television set.
Infrared waves are also known as heat waves.
The infrared thermometer measures the amount of infrared waves given out by our body to determine our body temperature.
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infrared thermometer
Uses of Visible LightVisible light is the only
type of EM wave that we can see. The colours that we see are actually light waves of different wavelengths.
Light is also used by plants for photosynthesis and for high speed data transmission through optical fibres.
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plants need light to makefood through photosynthesis
Uses of Ultraviolet WavesUltraviolet waves
is used in forgery detector.
Ultraviolet waves in sunlight cause our bodies to become tanned and help our bodies produce vitamin D.
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ultraviolet is used to checkfor real bank notes
Uses of Ultraviolet WavesUltraviolet is to
kill microbes and sterilise medical equipment.
Overexposure to ultraviolet which can cause skin cancer.
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an ultraviolet steriliser
ultraviolet causes tanning
Uses of X-rays
X-rays are used to produce images of the body’s internal organs and bones.
X-rays are also used in airports to scan luggages for prohibited items.
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doctor studying an X-ray film
Uses of Gamma raysGamma rays are used
in radiation therapy. These high energy rays are directed at cancer cells to kill them.
Gamma rays can also be used to sterilise medical equipment.
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international radiation hazard sign
Activity Book LinkActivity 2.3Uses of Electromagnetic Waves
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