# SCIENCE physics

• Created by: Abbie
• Created on: 15-05-13 19:27
They're electrons! Small and move fast. Penetrate moderately before colliding and are moderately ionising. Are stopped by a thin sheet of metal e.g. a few millimetres of aluminium.
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Big and heavy! Have 2 protons and 2 neutrons and are stopped quickly because they don't penetrate far into materials! can be stopped by paper/skin. They are strongly ionising as they bash into atoms and knock electrons off before slowing down.
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What happens when radiation enters human cells?
It can ionise molecules and damage DNA, causing mutations in the cell that could lead to Cancer.
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When are positive and negative ions formed?
Positive - when atoms lose electrons. Negative - when atoms gain electrons
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Ionisation - when atoms gain or lose electrons, turning them into ions.
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What happens when an unstable nucleus decays?
It gives off one or more kinds of nuclear radiation - gamma, beta, alpha.
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How do you measure the cost of energy?
Cost = Number of units x Price per unit
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How do you measure the amount of energy supplied?
Energy Supplied = power x time (h)
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How do you measure power?
Power (w) = Voltage (v) x current (a)
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What is power measured in?
Watts
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How do you work out energy efficiency?
(useful energy output/total energy input) x 100%
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How do you work out the total energy input?
Total energy input = useful energy output + waste energy output
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What is the dynamo effect?
Turning kinetic energy into electrical energy.
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In what situations can EM induction be used?
When an electrical conductor (a coil and wire is often used) moves through a magnetic field and when the magnetic field though an electrical conductor changes. If the direction of movement is reversed, then the voltage/current will be reversed too.
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What needs to be increased to get a bigger voltage?
The strength of the magnet, the number of turns on the coil, the speed of movement
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What do generators do?
Rotate a coil in a magnetic field.
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What is needed to transmit a lot of electrical power?
High voltage or a high current.
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A type of electromagnetic wave! No mass and no charge, can penetrate a long way into objects and have weak ionisation because they pass through instead of collide with atoms. Stopped by thick concrete or a few cm of Lead.
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## Other cards in this set

### Card 2

#### Back

Big and heavy! Have 2 protons and 2 neutrons and are stopped quickly because they don't penetrate far into materials! can be stopped by paper/skin. They are strongly ionising as they bash into atoms and knock electrons off before slowing down.

### Card 3

#### Front

What happens when radiation enters human cells?

### Card 4

#### Front

When are positive and negative ions formed?