JEE PYQ: Magnetic Effects Of Current Question 45
Question 45 - 2019 (09 Jan 2019 Shift 2)
One of the two identical conducting wires of length $L$ is bent in the form of a circular loop and the other one into a circular coil of $N$ identical turns. If the same current is passed in both, the ratio of the magnetic field at the central of the loop ($B_L$) to that at the centre of the coil ($B_C$), i.e. $\frac{B_L}{B_C}$ will be:
(1) $N$
(2) $\frac{1}{N}$
(3) $N^2$
(4) $\frac{1}{N^2}$
Show Answer
Answer: (4) $\frac{1}{N^2}$
Solution
$B_L = \frac{\mu_0 I}{2R}$, $B_C = \frac{\mu_0 N^2 I}{2R}$. $\frac{B_L}{B_C} = \frac{1}{N^2}$.
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