Two concentric and coplanar circular loops P and Q have their radii in the ratio 2 : 3. Loop Q carries a current 9 A in the anticlock wise direction. For the magnetic field to be zero at the common centre, loop P must carry
The correct answer is (D) 6 A in the clockwise direction. To nullify the magnetic field at the common center, the magnetic fields produced by both loops must be equal and opposite. Using the ratio of radii and currents, loop P must carry 6 A clockwise.
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