Question

As shown, three coils are given. The first and the last coils carry equal currents. Choose the correct option for the second inductor so that it has clockwise current.

• A. Move \(L_1\) towards \(L_2\) and \(L_3\) away from \(L_2\).
• B. Move \(L_1\) away from \(L_2\) and \(L_3\) away from \(L_2\).
• C. Move \(L_1\) towards \(L_2\) and \(L_3\) towards \(L_2\).
• D. Move \(L_1\) away from \(L_2\) and \(L_3\) towards \(L_2\).

Hint:

To solve electromagnetic induction problems:
First determine whether magnetic flux is increasing or decreasing
Then apply Lenz’s law to decide the direction of induced current
Treat effects of multiple sources separately and then combine

Answer 1

The Correct Option is A

Concept: 
Lenz’s law determines the direction of the induced current in a coil. According to Lenz's law, the induced current flows in such a way that it opposes the change in magnetic flux that produces it. The important aspects of this law are: - If the coils are approaching, they increase the magnetic flux. - If the coils are receding, they decrease the magnetic flux. - The induced current opposes the change in flux, not the flux itself. 
Step 1: **Effect of coil \(L_1\) on coil \(L_2\)**.
- The current in \(L_1\) is anticlockwise. - When \(L_1\) is moved towards \(L_2\), the magnetic flux through \(L_2\) increases. - To oppose this increase, according to Lenz's law, the induced current in \(L_2\) must generate a magnetic field opposite to that of \(L_1\), which leads to a clockwise current in \(L_2\). 
Step 2: **Effect of coil \(L_3\) on coil \(L_2\)**.
- The current in \(L_3\) is clockwise. - When \(L_3\) is moved away from \(L_2\), the magnetic flux through \(L_2\) decreases. - To oppose this decrease, the induced current in \(L_2\) must act to maintain the original flux direction. Therefore, the induced current in \(L_2\) must be clockwise. 
Step 3: **Combining both effects**.
Both actions—moving \(L_1\) towards \(L_2\) and moving \(L_3\) away from \(L_2\)—result in an induced current in \(L_2\) in the same (clockwise) direction. Hence, the current in the second coil, \(L_2\), will be clockwise in both cases. Therefore, the correct option is: \[ \boxed{\text{Correct option is (1)}} \]