Question

Three identical coils $A, B$, and $C$ carrying currents are placed coaxially with their planes parallel to one another. $A$ and $C$ carry currents as shown in figure. $B$ is kept fixed, while $A$ and $C$ both are moved toward $B$ with the same speed. Initially, $B$ is equally separated from $A$ and $C$. The direction of the induced current in the coil $B$ is

• A. same as that in coil A
• B. same as that in coil B
• C. zero
• D. none of these

Answer 1

Answer: (C)

Because $A$ and $C$ are at equal distance from $B$, and their flux across $B$ is in opposite direction, so at any time flux in $B$ will be zero. Hence no emf is induced.