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A student places a wire near a magnet - OCR Gateway - GCSE Physics - Question 21 - 2021 - Paper 1
Question 21
A student places a wire near a magnet. The wire is connected in series to a cell and a switch, as shown in the diagram. (a) Explain what will happen to the wire whe... show full transcript
Worked Solution & Example Answer:A student places a wire near a magnet - OCR Gateway - GCSE Physics - Question 21 - 2021 - Paper 1
Step 1
Explain what will happen to the wire when the switch is closed.
Answer
When the switch is closed, an electric current will flow through the wire. According to the right-hand rule, a magnetic field is created around the wire due to the current. This magnetic field interacts with the magnetic field of the magnet (which has north (N) and south (S) poles). As a result, the wire will experience a force due to this interaction, causing it to move. The wire could either be attracted towards the magnet or repelled, depending on the orientation of the magnetic fields.
Step 2
Calculate the magnetic flux density of the field.
Answer
To calculate the magnetic flux density (B), we can use the formula:
where:
- F = force acting on the wire = 0.15 N
- I = current through the wire = 5.0 A
- L = length of the wire = 0.25 m
Rearranging the equation to solve for B gives:
Substituting the known values:
This simplifies to:
Thus, the magnetic flux density of the field is 0.12 T.