A rectangular coil ABCD of N turns is suspended freely between the poles of a strong…
PHYSICS · Multi-part · CBSE · Physics · Moving Charges and Magnetism · Moving Charges and Magnetism
Problem
A rectangular coil ABCD of N turns is suspended freely between the poles of a strong horseshoe magnet. The long sides AB and CD are perpendicular to the uniform magnetic field, while the short sides BC and AD are parallel to the field. A steady current I is passed through the coil with the current entering at A and leaving at C.
Answer the following questions related to the motion of the coil:
(a) Identify the direction of the mechanical force acting on side AB and on side CD of the coil.
(b) Explain how these two forces together produce a couple (torque) on the coil, causing it to rotate.
(c) When the plane of the coil becomes parallel to the magnetic field, what will be the orientation of sides AB and CD with respect to the field and what happens to the turning moment at that instant?
(d) Describe qualitatively what will happen to the coil if the current I is increased while all other conditions remain unchanged.