JEE Main 2021 (31 Aug, Shift 1) Physics Q10: Biot-Savart Law

Question

A coil having N turns is wound tightly in the form of a spiral with inner and outer radii 'a' and 'b' respectively. Find the magnetic field at centre, when a current I passes through coil :

Accepted Answer

Option 1: $\frac{\mu_0 IN}{2(b-a)}\log_e\left(\frac{b}{a}\right)$

Answer

$\frac{\mu_0 IN}{2(b-a)}\log_e\left(\frac{b}{a}\right)$

Answer

$\frac{\mu_0 I}{8}\left(\frac{a-b}{a+b}\right)$

Answer

$\frac{\mu_0 I}{4(a-b)}\left[\frac{1}{a}-\frac{1}{b}\right]$

Answer

$\frac{\mu_0 I}{8}\left[\frac{a+b}{a-b}\right]$

JEE Main 31 August 2021, Shift 1, Physics Q10

Same idea in other shifts