A) maximum at the centre of the loop
B) zero at the centre of loop
C) zero at all points inside the loop
D) zero at all points outside of the loop
Correct Answer: B
Solution :
At point P, the current will divide in inverse ratio of resistance if arms PQRS and PS. \[i=1\,{{i}_{2}}=3\] Hence, at the centre of coil \[B=3B{{P}_{B}}\] \[=3\frac{{{\mu }_{0}}.1}{4\pi \frac{a}{2}}(sin{{45}^{o}}+sin{{45}^{o}})\] \[=3\frac{{{\mu }_{0}}.1}{4\pi a}\times 2\sqrt{2}\] ?(1) \[=1\times \frac{{{\mu }_{0}}\times 3i}{4\pi a}\times 2\sqrt{2}\] \[=3\frac{{{\mu }_{0}}i}{4\pi a}\times 2\sqrt{2}\] ?(2) From equation (1) and (2) we observe that these are equal and opposite Therefore, the magnetic field \[B=0\] at the centre.You need to login to perform this action.
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