PYQ NEET- Force And Torque Due To Magnetic Field

2016:

The answer is (A) 0.

The magnetic flux is given by Φ = BA cos θ. When the coil is rotated by 180° about its diameter, θ becomes 180°. Therefore, Φ = BA cos 180° = -BA.

2017:

The answer is (A) be doubled.

The magnetic flux is given by Φ = BA. When the radius of the loop is doubled, the area of the loop becomes 4 times. Therefore, the magnetic flux becomes 4 times if the magnetic field remains constant.