# Electromagnetic waves

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What are electromagnetic radiations and how do they travel?
Electric and magnetic disturbances that travel as waves and move energy from place to place
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Describe the speed of electromagnetic waves
They all travel through space(a vacuum) at the same speed (300 million m/s)but they all have different wavelengths and frequency
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Name the 7 different rays in the electromagnetic spectrum and an acronym to remember them by
Granny's X-box uses volts in my room. Gamma,X-ray,Ultra-violet,visible, infrared, microwaves, radio.
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What is the frequency and wavelength of the waves?
frequency: 10 to the power of 22, 18, 16, 15, 13, 10, 6. Wavelength:10 to the power of -15,-12,-8,-7,-4,-2,4
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What equation do we need to link the wave speed to their wavelength and frequency?
V=f×λ V =wave speed(3 million m/s) f= frequency λ=wave length in metres
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What is wave speed,frequency and wavelength measured in?
Wave speed=meters per second, frequency=hertz(Hz), wavelength=metres
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How does the material that the waves are used with make a difference?
Different wavelengths of electromagnetic radiation are reflected, absorbed or transmitted differently by different substances and types of surface
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Which part of the electromagnetic spectrum transfers the most energy?
The higher the frequency of an electromagnetic wave the more energy it transfers-Gamma rays.
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Why do we see colours?
Visible light is the part of the electromagnetic spectrum that can be detected by our eyes.We see the different wavelengths within it as different colours.
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For transmitting radio and TV programs and to carry mobile phone signals.
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What are microwaves used in?
Communications. Microwave transmitters produce wavelengths that are able to pass through the atmosphere. They are used send signals to and from satellites and within mobile phone networks.
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Infrared Radiation(IR) is emitted by all objects. The hotter, the more it emits. Remote controls for devices such as TVs and CD players use IR.
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Microwave radiation and radio waves penetrate your skin and are absorbed by body tissue. This can heat internal organs and damage them. Infrared radiation is absorbed by the skin;too much will burn your skin
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What effect does the amount of information carried have on wave length?
The shorter the wavelength the more information they carry, the shorter their range, the less they spread out.
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By applying an alternating voltage to the aerial.
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What is sometimes thought of phones and their effect on people?
Some scientists think that the radiation from mobile phones may affect the brain, especially on children.
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What are optical fibres?
Optical fibres are very thin glass fibres. We use them to transmit signals carried by visible light or infrared radiation. The signals travel down the fibre by repeated total internal reflection.
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Why are optical fibres useful?
Optical fibres carrying visible light or infrared are useful in communications because they could carry much more information and are more secure than radiowaves and microwave transmissions.
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What is the doppler effect?
A wave source is moving relative to an observer, the wavelength and frequency of the waves detected by the observer will have changed(shifted) from the original produced by the source. This is called the Doppler effect
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How the doppler effect can be demonstrated with sound waves?
For example, an ambulance siren will sound different depending on whether it is moving away from you(the pitch is lower) or towards you(the pitch is higher)
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What happens to the wavelength and frequency when the source moves away from and towards the observer during?
When the source moves away from the observer, the observed wavelength increases and the frequency decreases. When the source moves towards the observer the observed wavelength decreases and the frequency increases.
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What is red-shift?
Light observed from distant galaxies has been shifted towards the red end of the spectrum. This is known as the red shift ans that means that he frequency has decreased and the wavelength has increased.
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What is blue shift?
A blue shift would indicate that a galxy is moving towards us. We are able to see these effects by observing dark lines in the spectra from galaxies
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What does the red shift suggest?
The further away a galaxy, the bigger the red shift. This suggests that distant galaxies are moving away from us, and the most distant galaxies are moving away the fastest. This is true of galaxies no matter which direction you look.
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What does it mean that the galaxies are moving away from each other?
All the distant galaxies are moving away from each other, so the whole universe is expanding.
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Where did the big bang theory come from?
The universe is now expanding outwards, this suggests that it started with a massive explosion at a very small initial point. This is known as the big bang theory.
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What is cosmic microwave background radiation?
CMBR was produced by the big bang If the universe began with a big bang, then high energy gamma radiation would have been produced. As the universe expanded this would have become lower-energy radiation. which is the only way to explain CMBR. .
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What happens to the wavelength of radiation as it changes from gamma to microwave?
The wavelength increases
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## Other cards in this set

### Card 2

#### Front

Describe the speed of electromagnetic waves

#### Back

They all travel through space(a vacuum) at the same speed (300 million m/s)but they all have different wavelengths and frequency

### Card 3

#### Front

Name the 7 different rays in the electromagnetic spectrum and an acronym to remember them by

### Card 4

#### Front

What is the frequency and wavelength of the waves?

### Card 5

#### Front

What equation do we need to link the wave speed to their wavelength and frequency?

#### Back

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An effective way of revising is doing lots of practice questions. But first we need to know the content.

So here are a bunch of questions on electromagnetic waves. Try and answer them all and then check if they are correct by using your revision guide or revision notes from the internet.

Report

the cards are usefull but its annotu=ing having to click everytime

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