A straight wire of diametre 0.5 mm carrying a current of 1 A is replaced by another wire of 1mm diametre carrying same current. The strenth of magnetic field far away is

Options

A. twice the earlier value
B. same as the earlier value
C. one - half of the earlier value
D. one - quarter of the earlier value

Answer

B

Explanation

`B=(mu_0i)/(2pir)` and so it is independent of thickness.
The current is same in both the wires, hence magnetic tiled induced will be same.