Science (086) — AI-generated practice question

At every point on a current-carrying circular loop, the magnetic field lines form concentric circles. As we move toward the centre of the loop, these circles become larger and larger, so their arcs appear as parallel straight lines at the centre. By the right-hand rule, every section of the wire contributes field lines in the same direction within the loop, reinforcing this parallel pattern.

Effect of increasing turns: If the coil has n turns, the magnetic field at the centre becomes n times stronger than that of a single turn, because the current in each turn flows in the same direction and the fields due to all turns add up.

Source: Chapter 12, Section 12.2.3

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• The key idea is that large arcs of concentric circles look like straight lines — this is the geometric reason examiners expect you to state.
• Mention the right-hand rule to show all sections reinforce field in the same direction.
• For the second part, the formula "n times" with the reason (same direction → fields add up) earns the mark.
• Avoid writing about solenoids here; this question is strictly about circular loops.