Question

A cylindrical conductor of radius R is carrying

a constant current. The plot of the magnitude

of the magnetic field. B with the distance d

from the centre of the conductor, is correctly

represented by the figure :

B

Accepted Answer

**Magnetic field inside conductor**

$$B = \frac{\mu_0 i}{2\pi R^2} d$$

$$	ext{or } B = Kd \quad \dots(i)$$

Straight line passing through origin

**At surface** ($d = R$)

$$B = \frac{\mu_0 i}{2\pi R} \quad \dots(ii)$$

Maximum at surface

**Outside** (d > R)

$$B = \frac{\mu_0 i}{2\pi d}$$

$$	ext{or } B \propto \frac{1}{d} 	ext{ (Hyperbolic)}$$