P1b Revision Guide

Revision Booklet outlining the key information for each topic

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  • Created on: 01-01-12 16:10
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Isambard Community School
P1b: Electromagnetic Spectrum,
Radioactivity and Universe.
Properties of Light and Waves
What do we already know about light?
· White light is made up of 7 colours. (Red, Orange, Yellow, Green, Blue,
Indigo and Violet)
· Light travels in straight lines.
· Light can be reflected.
· Light can be refracted (bent).
· Light can be absorbed.
What other things do we need to know for our GCSE?
· Light travels in waves.
· Light transfers energy from one place to another.
· Visible light (light that we see) is part of the electromagnetic spectrum.
(We will come back to this later)
Light waves are affected by two things: Wavelength ­ the
· Its wavelength ( ) ­ how long it is. distance between to
identical points on the
· Its frequency (f) ­ how many waves
pass a certain point in 1s. Frequency is
measured in Hertz (Hz) Wavelength
Remember ­ waves transfer energy and not
matter! Therefore, waves of different
wavelengths have different effects.
The diagram shows one complete wave.
Isambard Community School Mr Scutt, 2009

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Speed (v):
If you know the wavelength and frequency of a wave, then you can calculate its
Wave speed (m/s) = frequency (Hz) x wavelength (m)
All electromagnetic waves travel at 300 000 000 m/s through space or in a
A mobile phone gives out electromagnetic waves of frequency 900 million Hz.
Calculate the wavelength of these waves.
Wavelength (m) = Wave speed (m/s) v
Frequency (Hz)
300 000 000 m/s
900 000 000 Hz = 0.…read more

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When a wave meets some matter, like glass or air, three things can happen?
· Radiation can be transmitted ­ like light passes through glass.
· It can be reflected ­ bounce back, like a mirror.
· It can be absorbed ­ the energy is transferred to the matter.
Electromagnetic Waves Absorbing electromagnetic (EM)
What affects how the waves respond? radiation has two effects:
· The colour of the object · The substance gets hotter.…read more

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A summary of the different Electromagnetic waves and their properties are
shown below:
Electromagnetic Where are they used? Additional features and properties
Radio Televisions Lowest frequency electromagnetic wave
Communication (radios and Longest wavelength electromagnetic wave
mobile phones) Use alternating current to produce a signal.
The higher the frequency the more
information they carry, shorter the range,
more direct signal
Microwave Cook food Transfer kinetic energy to water molecules
Communication (from in food.
satellites) Can penetrate the atmosphere without
significant energy loss.…read more

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Electromagnetic waves are used for communication ­ radio, microwaves, visible
and infra-red.
The type of waves that is used to transmit a message is important.
Radio Waves
Low frequency (up to 3 MHz) radio
waves travel along the Earth's
surface and can travel hundreds of
miles. These ground waves are used
for local and national radio.
High frequency radio waves (3­30 MHz) are
reflected off the ionosphere high in the
atmosphere. These sky waves are used for
international and amateur radio.…read more

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Information is passed via waves. Lets have a closer look at them.
Analogue Wave:
Amplitude varies continuously
Frequency varies continuously
It can have any value within a range.
Where used:- Dimmer switches,
thermometers, speedometers
and old-fashioned watches.
Digital Wave:
These are coded pulses.
Only made up of two values ­ 1 `on, or 2 `off'.
Where used:
On/off switches, digital clocks and meters.…read more

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Over large distances, waves lose energy and therefore need boosting (amplifying).
As they travel they also pick up interferences or noise from electrical
disturbances or other signals.
It is difficult to know what the original signal was. During amplification you also
amplify the noise.
An example of amplification of an analogue wave is shown below:
An Digital Wave:
This is a better wave.
Noise is less of a problem. You can work out what the original signal was.…read more

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Isambard Community School Mr Scutt, 2009…read more

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Many elements have different isotopes.
An isotope is an atom with same number of protons but a different number of
e.g. Carbon-14 and Carbon-12
Other isotopes tend to be radioactive as their nucleus is unstable, so decays
(breaks down) and emits radiation. Carbon-14 is an unstable isotope.
Radioactive Decay
Decay is a random process.
You can not say when decay is going to happen.
You can not do anything to make decay happen. It is not affected by
temperature or chemical bonding.…read more

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Alpha Radiation ():
· Helium nuclei ( 2 He)
· Particles are relatively big, heavy and slow
· Do not penetrate far ­ stopped quickly by paper,
skin or few cm's of air. Therefore, are strongly
· Electrically charged (positive) ­ therefore are deflected by electric field
and magnetic fields.
Beta Radiation ():
· Is an electron ( 0-1 e) formed when a neuron turn to a proton and an
· For every electron emitted, the nucleus gains one proton.…read more



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