A bar magnet of magnetic moment of `5*0Am^2` has poles `20cm` apart. Calculate the pole strength.

Explanation

To solve the problem of finding the pole strength of a bar magnet given its magnetic moment and the distance between its poles, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Magnetic moment (M) = \(5 \, \text{A m}^2\)
- Distance between the poles (2L) = \(20 \, \text{cm}\)

2. **Convert the Distance to Meters:**
- Since \(1 \, \text{cm} = 0.01 \, \text{m}\), we convert \(20 \, \text{cm}\) to meters:
\[ 2L = 20 \, \text{cm} = 20 \times 0.01 \, \text{m} = 0.2 \, \text{m} \]

3. **Calculate the Half Distance (L):**
- The distance from the center of the magnet to one pole (L) is half of 2L:
\[ L = \frac{2L}{2} = \frac{0.2 \, \text{m}}{2} = 0.1 \, \text{m} \]

4. **Use the Formula for Magnetic Moment:**
- The magnetic moment (M) of a bar magnet is given by the formula:
\[ M = m \cdot 2L \]
where \(m\) is the pole strength.

5. **Rearrange the Formula to Find Pole Strength (m):**
- Rearranging the formula to solve for \(m\):
\[ m = \frac{M}{2L} \]

6. **Substitute the Values:**
- Now substituting the known values into the equation:
\[ m = \frac{5 \, \text{A m}^2}{0.2 \, \text{m}} = \frac{5}{0.2} \, \text{A} = 25 \, \text{A} \]

7. **Final Answer:**
- The pole strength of the bar magnet is \(25 \, \text{A}\).

### Summary of the Solution:
The pole strength of the bar magnet is calculated to be \(25 \, \text{A}\).