AQA GCSE Magnetic field around a wire(Physics)
Magnetic Field Around a wire.
When a current flows along a wire two things happen:
1.Magnetic field is created around the wire
2. Wire becomes hot
Further from the wire, the magnetic field lines are further apart. This is because the further you are from the wire, the weaker the magnetic field.
When the current flows down the wire, the magnetic field is clockwise.
When the current flows up the wire, the magnetic field is anticlockwise.
So, reversing the current direction will reverse the magnetic field.
Factors that affect the size of the magnetic field around the wire.
The size of the magnetic field around the wire depends on:
1.Current flowing through the wire
2.Distance from the wire
As the current flowing through the wire increases, the magnetic field strength increases, so the magnetic field lines will be closer together
As distance from the wire increases, magnetic field strength decreases, so the magnetic field lines will be further apart.
Right hand grip rule
The right hand grip rule is used to predict either the direction of the current flowing along a wire, or the direction of a magnetic field around a wire.
In the diagram below, the thumb points upwards so the current is flowing upwards through the wire, whilst the fingers are wrapping around the wire in an anticlockwise direction, so the magnetic field is anticlockwise.
Try this for yourself, using a pencil to hold.
Practice Question
1.What happens when a current flows along a wire?
2.State the names of two factors that affect the strength of a magnetic field around a wire
3. Use the image of the wire below to answer the following question
Using an arrow draw the direction of the magnetic field on the diagram above.
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