Question

Two circular coils A and B are facing each other as shown in figure. The current i through A can be altered

• A. There will be repulsion between A and B if i is increased
• B. There will be attraction between A and B if i is increased
• C. There will be neither attraction nor repulsion when i is changed
• D. Attraction or repulsion between A and B depends on the direction of currer depend whether the current is increased or decreased

Answer 1

The correct option is A There will be repulsion between A and B if i is increased

A current is induced in the coil $B$. When the current in the coil $A$ is changed, the magnetic field associated with it also changes. As coil $B$ is placed close to $A$, hence magnetic field lines around this coil also change. Due to change in magnetic field lines associated with coil $B$, an induced current is also induced in it.