Question

An iron rod of length l is bent into semi circle wire what will be its magnetic moment now

Answer 1

As we know that

Magnetic moment = current flowing through the wire x area of circle formed

Mm= I x A

Here, we can write , 2πr= L

Or. r= L/2π.

Area of circle formed= π r²= π (L/2π)²

Or A= L/ 4π

Hence , Mm= I x A = I x L/4π