JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
A circular loop of radius \(r\) is carrying current I A. The ratio of magnetic field at the centre of circular loop and at a distance \(r\) from the center of the loop on its axis is:
- A \(1: 3 \sqrt{2}\)
- B \(3 \sqrt{2}: 2\)
- C \(2 \sqrt{2}: 1\)
- D \(1: \sqrt{2}\)
Answer & Solution
Correct Answer
(C) \(2 \sqrt{2}: 1\)
Step-by-step Solution
Detailed explanation
Magnetic field due to current carrying circular loop on its axis is given as \(\frac{\mu_0 ir ^2}{2\left( r ^2+ x ^2\right)^{3 / 2}}\) At centre, \(x=0, B_1=\frac{\mu_0 i }{2 r }\) At \(x=r, B_2=\frac{\mu_0 i}{2 \times 2 \sqrt{2 r}}\) \(\frac{ B _1}{ B _2}=2 \sqrt{2}\)
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