Find the magnetic field B at the centre of a rectangular loop of length l and width b, carrying a current i.

Explanation

To find the magnetic field \( B \) at the center of a rectangular loop of length \( l \) and width \( b \) carrying a current \( i \), we can follow these steps:

### Step 1: Understand the Geometry of the Loop
We have a rectangular loop with length \( l \) and width \( b \). The center of the loop is the point where we want to calculate the magnetic field. The distances from the center to the sides of the rectangle are \( \frac{l}{2} \) and \( \frac{b}{2} \).

### Step 2: Identify Contributions from Each Side
The magnetic field at the center due to each side of the rectangle needs to be calculated. The loop has four sides, and we will consider the contributions from opposite sides.

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