What is a solenoid ? When does a solenoid behave as a magnet ? Draw the pattern of the magnetic field produced inside it showing the directions of the magnetic field lines.
Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer
Solenoid: A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.
When it behaves as a magnet: When electric current flows through a solenoid, one end behaves as a north pole and the other as a south pole, just like a bar magnet.
Diagram:
```
N |————————————————————| S
→ → → → → → →
→ → → → → → →
→ → → → → → →
```
(Field lines inside are parallel and straight, indicating a uniform magnetic field directed from S-pole end to N-pole end inside the solenoid.)
Source: Chapter 12, Section 12.2.4
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Explanation
- Definition (1 mark): Must mention "many circular turns," "insulated copper wire," and "cylindrical shape."
- Condition (1 mark): Current must flow through it; one end = N pole, other = S pole.
- Diagram (1 mark): Show parallel, equally spaced, straight field lines inside pointing from south to north end (inside the solenoid). Examiners check that lines are parallel and the direction is marked. Even a neat sketch with arrows scores full marks.