The magnetic field at the centre of a current carrying circular loop of radius R is 16 μ ~T. The magnetic field at a distance x=√3 R on its axis from…
JEE Main 2026 — Physics Electromagnetism
2026mcqmedium
The magnetic field at the centre of a current carrying circular loop of radius R is 16μT. The magnetic field at a distance x=3R on its axis from the centre is ____μT.
Official previous-year question
Held on 28 Jan 2026 · Verified 6 Jul 2026.
Options
A
4
B
2
C
22
D
8
Did you get this right?
Sign in to track your attempts and accuracy.
Solution
The magnetic field at the center of a circular loop is Bcenter=2Rμ0I=16μ T.
On the axis at distance x from center: B(x)=2(R2+x2)3/2μ0IR2.
At x=3R: B(3R)=2(R2+3R2)3/2μ0IR2=2(4R2)3/2μ0IR2=16Rμ0I.
The ratio: BcenterB(3R)=1/2R1/16R=81.
Therefore: B(3R)=81×16μ=2μ T.
Your note
Sign in to keep a private note on this question. Nothing you write is ever public.