JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
Two identical long current carrying wires are bent into the shapes shown in the following figures. If the magnitude of magnetic fields at the centres P and Q of a semicircular arc are \(B_1\) and \(B_2\) respectively, then the ratio \(\dfrac{B_1}{B_2}\) is _______.
- A \(\dfrac{2 + \pi}{1 + \pi}\)
- B \(\dfrac{1 + \pi}{1 - \pi}\)
- C \(\dfrac{2 + \pi}{1 - \pi}\)
- D \(\dfrac{1 + \pi}{2 - \pi}\)
Answer & Solution
Correct Answer
(A) \(\dfrac{2 + \pi}{1 + \pi}\)
Step-by-step Solution
Detailed explanation
For the first figure, the magnetic field at the centre P is the vector sum of the magnetic fields due to two semi-infinite straight wires and one semicircular arc. The magnetic field due to the top semi-infinite wire at P is \(B_{1a} = \dfrac{\mu_0 I}{4\pi r}\) directed into the…
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