Two conducting coils are placed co - axially now a cell is connected in one coil then they will :

Options

A. attract to each other
B. repel to each other
C. both (1) & (2)
D. they will not experience any force

Answer

To solve the problem regarding the interaction of two coaxial conducting coils when a cell is connected to one of them, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Setup**:
- We have two conducting coils placed coaxially. Let's label them as Coil 1 (outer coil) and Coil 2 (inner coil).
- A cell (battery) is connected to one of the coils. For this explanation, we will assume it is connected to Coil 1.

2. **Direction of Current**:
- When the cell is connected to Coil 1, a current flows through it. The direction of this current can be determined using the right-hand rule. If we assume the current flows in a clockwise direction when viewed from one end, we can visualize this.

3. **Magnetic Field Creation**:
- According to Ampère's circuital law, a current-carrying coil generates a magnetic field. For Coil 1, the magnetic field will be directed along the axis of the coil. Using the right-hand rule, we can determine that the magnetic field at the center of Coil 1 (inside the coil) will be directed upwards.

4. **Effect on Coil 2**:
- Coil 2, being placed within the magnetic field created by Coil 1, will experience a change in magnetic flux due to the current in Coil 1. According to Faraday's law of electromagnetic induction, a change in magnetic flux through a coil induces an electromotive force (emf) in that coil.

5. **Direction of Induced Current in Coil 2**:
- According to Lenz's law, the direction of the induced current in Coil 2 will be such that it opposes the change in magnetic flux. Since the magnetic field from Coil 1 is directed upwards, the induced current in Coil 2 will flow in a direction that creates a magnetic field opposing this upward direction. Thus, the induced current in Coil 2 will flow in a counterclockwise direction when viewed from the same end.

6. **Interaction Between the Coils**:
- Since the currents in Coil 1 and Coil 2 are in opposite directions (Coil 1 has a clockwise current and Coil 2 has a counterclockwise current), the coils will repel each other. This is due to the fact that parallel currents attract and anti-parallel currents repel.

### Conclusion:
When a cell is connected to one of the coaxial coils, the two coils will repel each other due to the opposing directions of the induced currents.