A bar magnet has coercivity `4xx10^(3) Am^(-1)`. It is desired to demagnetise it by inserting it inside a solenoid `12 cm` long and having `60` turns. The current that should be sent through the solenoid is

1. 8 A
2. 6 A
3. 4.5 A
4. A

Options

A. 8 Å
B. 6 Å
C. 4.5 Å
D. 2 Å

Explanation

To solve the problem, we need to determine the current required to demagnetize a bar magnet with a given coercivity when placed inside a solenoid. Here are the steps to find the solution:

### Step 1: Understand the given parameters
- Coercivity (H) = \(4 \times 10^3 \, \text{A/m}\)
- Length of the solenoid (L) = 12 cm = 0.12 m (conversion from cm to m)
- Number of turns (N) = 60 turns

### Step 2: Calculate the magnetic field strength (H)
...