A circular coil of wire has 50 turns. Compared to a single-turn coil of the same size carrying the same curre…

Question

A circular coil of wire has 50 turns. Compared to a single-turn coil of the same size carrying the same current, the magnetic field at the centre of the 50-turn coil is:
(A) 50 times smaller
(B) The same
(C) 50 times larger
(D) 2500 times larger

Accepted Answer

## Model Answer **(C) 50 times larger** The magnetic field at the centre of a circular coil is *n* times that of a single turn, since the field due to each turn adds up in the same direction. ## Explanation The key principle (stated directly in section 12.2.3) is: *"if there is a circular coil having n turns, the field produced is n times as large as that produced by a single turn."* For n = 50, the field is simply 50 times larger — not 2500 times (that would be n², which is incorrect here).

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