A long straight wire of radius 10mm carries a current uniformly distributed over its cross section. The ration of magnetic fields due to the wire at distance of 5mm and 15 mm, respectively from the axis of the wire is

Options

A. (a)`(3)/(4)`
B. (b)`(2)/(3)`
C. (c)`(1)/(3)`
D. (d)2

Explanation

To solve the problem of finding the ratio of magnetic fields due to a long straight wire at distances of 5 mm and 15 mm from its axis, we can follow these steps:

### Step 1: Understand the Magnetic Field Inside and Outside the Wire
For a long straight wire carrying a uniformly distributed current \( I \):
- Inside the wire (at a distance \( r < R \), where \( R \) is the radius of the wire), the magnetic field \( B \) is given by:
\[ B = \frac{\mu_0 I r}{2 \pi R^2} \]
...