Question

Derive an expression for magnetic field produce due to flow pf current in straight wire

Answer 1

When Current passes through a straight wire then a magnetic field is produced around that wire. Now, we find the expression for that magnetic field

Explanation:

Force on a single charge q moving with the drift velocity Vd  is  

Fs = qvdBsinθ

Force on N charges will be  

Ft = N×qvdBsinθ

and N=nV where, “n” is charge per unit carrier and “V” is volume which is equal to “Al”. So,

Ft = (Aqnvd)lBsinθ

And  

Aqnvd = I

So,  

Ft = IlBsinθ

And,

B = Ft / Ilsinθ