AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
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. The magnetic field inside a solenoid is strong and uniform.
A solenoid is a coil of insulated wire, often wound around a soft iron core.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 2 of 6
- 2 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A solenoid is a coil of insulated wire, often wound around a soft iron core. Winding a current-carrying wire into a solenoid concentrates the magnetic field lines inside the coil, making the field much stronger than around a straight wire carrying the same current. Inside the solenoid, the field lines are parallel and evenly spaced, so the field is strong and uniform. Outside, the field resembles that of a bar magnet, with a north and south end. Adding more turns, increasing the current, or inserting a soft iron core further strengthens the field. This makes solenoids useful in electromagnets, relays and loudspeakers.
What earns the marks
- Forming a wire into a solenoid increases the strength of the magnetic field compared with a straight wire.
- The magnetic field inside a solenoid is strong and uniform.
- Inside the solenoid, field lines are parallel and evenly spaced.
- The field outside a solenoid resembles the field of a bar magnet.
- Increasing the number of turns or the current increases the field strength of a solenoid.
- Adding a soft iron core increases the strength of the magnetic field of a solenoid.
Common mistakes and how to put them right
Thinking the field inside a solenoid is weak because it is inside the coil.
Put it right by stating that the field inside is strong and uniform.
Believing the field inside a solenoid is circular like around a straight wire.
Put it right by describing the field inside as parallel straight lines.
Assuming the field outside a solenoid is uniform.
Put it right by explaining that outside the field is like a bar magnet and is not uniform.
Exam tips
- When comparing a straight wire and a solenoid, state that the solenoid concentrates the field and makes it stronger.
- Use the phrase 'strong and uniform' when describing the field inside a solenoid, and support it by referring to parallel, evenly spaced field lines.
- If asked to increase the field strength of a solenoid, mention increasing current, increasing turns, or adding a soft iron core.
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. The magnetic field inside a solenoid is strong and uniform. 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?
Listen
A solenoid is a coil of insulated wire, often wound around a soft iron core. Winding a current-carrying wire into a solenoid concentrates the magnetic field lines inside the coil, making the field much stronger than around a straight wire carrying the same current. Inside the solenoid, the field lines are parallel and evenly spaced, so the field is strong and uniform. Outside, the field resembles that of a bar magnet, with a north and south end. Adding more turns, increasing the current, or inserting a soft iron core further strengthens the field. This makes solenoids useful in electromagnets, relays and loudspeakers. A strong answer earns marks for these points. Forming a wire into a solenoid increases the strength of the magnetic field compared with a straight wire. The magnetic field inside a solenoid is strong and uniform. Inside the solenoid, field lines are parallel and evenly spaced. The field outside a solenoid resembles the field of a bar magnet. A common slip: Thinking the field inside a solenoid is weak because it is inside the coil. Instead, stating that the field inside is strong and uniform. Exam tip: When comparing a straight wire and a solenoid, state that the solenoid concentrates the field and makes it stronger.
See it
Key words
Say what each word means before you turn the card.
Solenoid
Try answering aloud or in your head before turning the card.
Soft iron core
Try answering aloud or in your head before turning the card.
See every definition
- Solenoid
- A wire shaped into a coil, which increases the strength of the magnetic field created by a current through the wire.
- Soft iron core
- A core that, when inserted, further strengthens the magnetic field of 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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