JEE Mains · Physics · STD 12 - Moving charges and magnetism
- JEE Mains 2020
- Hard
- MCQ
A wire \(A\), bent in the shape of an arc of a circle, carrying a current of \(2\, A\) and having radius \(2\, cm\) and another wire \(B ,\) also bent in the shape of arc of a circle, carrying a current of \(3\, A\) and having radius of \(4\, cm ,\) are placed as shown in the figure. The ratio of the magnetic fields due to the wires \(A\) and \(B\) at the common centre \(O\) is
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Answer & Solution
Correct Answer
(C) \(6:5\)
Step-by-step Solution
Detailed explanation
Given \(i_{A}=2, r_{A}=2 cm , \theta_{A}=2 \pi-\frac{\pi}{2}=\frac{3 \pi}{2}\)
\(i_{B}=3, r_{B}=4 cm , \theta_{B}=2 \pi-\frac{\pi}{3}=\frac{5 \pi}{3}\)
\(B=\frac{\mu_{0} I \theta}{4 \pi R}\)
\(\frac{B_{A}}{B_{B}}=\frac{I_{A}}{I_{B}} \times \frac{\theta_{A} R_{B}}{\theta_{B} R_{A}}=\frac{6}{5}\)
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