In an experiment, a magnet with its magnetic moment along the axis of circular coil and directed towards the coil, is withdrawn away from the coil and parallel to itself. The current in the coil, as seen by the withdrawing magnet, is

Options

A. zero
B. clockwise
C. anti clockwisc
D. first .a. then .b.

Answer

To solve the problem, we need to analyze the situation involving electromagnetic induction as described in the question. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Setup
We have a circular coil and a magnet. The magnet is initially positioned such that its magnetic moment is aligned with the axis of the coil and directed towards it. As the magnet is withdrawn, we need to consider the effect on the magnetic flux through the coil.

**Hint:** Visualize the setup with the magnet and coil. Remember that the magnetic moment indicates the direction of the magnetic field produced by the magnet.

### Step 2: Determine the Change in Magnetic Flux
When the magnet is withdrawn from the coil, the magnetic field lines that pass through the area of the coil decrease. This means that the magnetic flux through the coil is decreasing.

**Hint:** Recall that magnetic flux (Φ) is given by the product of the magnetic field (B) and the area (A) through which it passes, and consider how moving the magnet affects this.

### Step 3: Apply Faraday's Law of Electromagnetic Induction
According to Faraday's law, a change in magnetic flux through a coil induces an electromotive force (EMF) in the coil. The induced EMF generates a current in the coil.

**Hint:** Remember that the induced EMF is proportional to the rate of change of magnetic flux.

### Step 4: Use Lenz's Law to Determine the Direction of Induced Current
Lenz's law states that the direction of the induced current will be such that it opposes the change in magnetic flux. Since the magnetic flux is decreasing as the magnet is withdrawn, the induced current will act to oppose this decrease.

**Hint:** Think about how the coil can create a magnetic field that opposes the reduction of the magnetic field from the magnet.

### Step 5: Determine the Direction of the Induced Current
To oppose the decrease in magnetic flux (which is directed into the coil), the induced current must create a magnetic field that is directed into the coil. For a circular coil, if the current flows in a clockwise direction when viewed from the position of the withdrawing magnet, it will produce a magnetic field directed inward.

**Hint:** Use the right-hand rule: curl your fingers in the direction of the current, and your thumb will point in the direction of the magnetic field produced by the coil.

### Conclusion
The induced current in the coil, as seen by the withdrawing magnet, is clockwise.

**Final Answer:** Clockwise