Question

Two coils of wires A and B are mutually at right angles to each other as shown in the figure. If the current in one coil is changed, then in the other coil ________

• A. No current will be induced.
• B. Current will be induced in clockwise direction.
• C. Current will be induced in anti-clockwise direction.
• D. Current will be induced depending on increasing or decreasing current.

Answer 1

Answer: (A)

No current will be induced.

Answer 2

When two coils are mutually at right angles, the magnetic field lines produced by one coil lie in the plane of the other coil. This means the angle between the magnetic field vector and the area vector of the second coil is 90 degrees. Consequently, the magnetic flux through the second coil is zero ($\Phi = BA \cos 90^\circ = 0$). Since the magnetic flux is always zero, its rate of change with respect to time ($d\Phi/dt$) is also zero. According to Faraday's Law of Electromagnetic Induction ($\varepsilon = -d\Phi/dt$), no EMF is induced, and therefore, no current will be induced in the second coil.