AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
Shaping a wire to form a solenoid increases the strength of the magnetic…
Full specification wording
Electromagnetism: Shaping a wire to form a solenoid increases the strength of the magnetic field created by a current through the wire.
A solenoid is a long coil of wire.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 3 of 9
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A solenoid is a long coil of wire. Each turn carries the same current the same way round, so each produces its own circular field, and where the turns sit side by side those fields point the same way inside the coil and add together, while outside the coil neighbouring contributions largely cancel. The result is a much stronger field inside for exactly the same current, which is why shaping a wire into a solenoid is one of the two changes AQA credits for strengthening the field around a current carrying wire, the other being increasing the current. Winding more turns into the same length strengthens the field again, because there are more contributions to add.
What earns the marks
- Stating that shaping the wire into a solenoid increases the strength of the magnetic field.
- Explaining that the fields due to the individual turns add together inside the coil.
- Stating that increasing the number of turns increases the field strength for the same current.
- Giving increasing the current as the other change that strengthens the field.
Common mistakes and how to put them right
Saying the coil concentrates the current rather than adding the fields of the turns.
Arguing the field is stronger because the longer wire has a greater resistance.
Claiming that adding more turns increases the current in the circuit.
Naming the iron core when the question asks only about shaping the wire.
Exam tips
- A 'give two changes' question wants two genuinely different ideas, so do not repeat yourself.
- Keep current, number of turns and core as three separate factors.
- Explain by adding fields, which is the reason the mark scheme is looking for.
Try the lesson
The start of the Electromagnetism: Shaping a wire to form a solenoid increases the strength of the magnetic field created by a current through the wire. lesson, made from checked teaching notes for this specification point.
Have a go first
A student coils a current-carrying wire into a solenoid. Compared with the same wire left straight, what happens to the magnetic field produced?
Listen
A solenoid is a long coil of wire. Each turn carries the same current the same way round, so each produces its own circular field, and where the turns sit side by side those fields point the same way inside the coil and add together, while outside the coil neighbouring contributions largely cancel. The result is a much stronger field inside for exactly the same current, which is why shaping a wire into a solenoid is one of the two changes AQA credits for strengthening the field around a current carrying wire, the other being increasing the current. Winding more turns into the same length strengthens the field again, because there are more contributions to add. A strong answer earns marks for these points. stating that shaping the wire into a solenoid increases the strength of the magnetic field. explaining that the fields due to the individual turns add together inside the coil. stating that increasing the number of turns increases the field strength for the same current. giving increasing the current as the other change that strengthens the field. Exam tip: A 'give two changes' question wants two genuinely different ideas, so do not repeat yourself.
See it
Key words
Say what each word means before you turn the card.
solenoid
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adding fields of turns
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number of turns
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increasing the current
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See every definition
- solenoid
- A long coil of wire, and shaping a wire into one increases the strength of the magnetic field created by a current through the wire.
- adding fields of turns
- Each turn carries the same current the same way round, so where the turns sit side by side their fields point the same way inside the coil and add together.
- number of turns
- Winding more turns into the same length strengthens the field again, because there are more contributions to add.
- increasing the current
- One of the two changes that strengthens the field around a current carrying wire, the other being shaping the wire into a solenoid.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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