Write an expression of magnetic flux density .B. at a point in end-on position or an axial position of a magnetic dipole. (Derivation not required.)

Explanation

To find the expression for the magnetic flux density \( B \) at a point in the end-on position (or axial position) of a magnetic dipole, we can follow these steps:

### Step 1: Understand the Setup
We have a bar magnet with a length of \( 2L \). The north pole is at one end and the south pole is at the other end. We want to find the magnetic flux density at a point \( P \) located along the axis of the magnet at a distance \( R \) from the center of the magnet.

### Step 2: Define the Magnetic Dipole Moment
The magnetic dipole moment \( m \) of the bar magnet is defined as:
\[
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