Sahay Sir > Question Answers > NEET Last 32 Years Solved 1988 - 2019 Physics and Chemistry Video Solutions > Physics > Chapter 23 - Magnetic Effects of Current and Moving Charges > A 250- Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 μA and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 1800 against the torque is

A 250- Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 μA and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 1800 against the torque is

A long straight wire of radius a carries a steady current I. The current is uniformly distributed over its cross-section. The ratio o the magnetic fields B and B′ at radial distances a/2​ and 2a respectively from the axis of the wire is