Question

A hollow cylinder with an inner radius of 4 mm and an outer radius of 25 mm conducts a 4-A current flowing parallel to the axis of the cylinder. If the current density is uniform throughout the wire, what is the magnitude of the magnetic field at a point 17 mm from its center? (μ 0 = 4π × 10-7 T · m/A)

Answer 1

2.1 × 10⁻⁵ T

Step-by-step explanation:

Given:

Inner radius, r = 4 mm = 0.004 m

Outer radius, R = 25 mm = 0.025 m

Current, I = 4 A

Distance of the point from the center, a = 17 mm = 0.017 m

μ₀ = 4π × 10⁻⁷ T·m/A

Now,

For the hollow cylinder magnetic field (B) is given as:

`B=\frac{\mu_0 I(a^2-r^2)\textup{}}{2\pi a(R^2-r^2)\textup{}}`

on substituting the respective values, we get

`B=\frac{4\pi*10^(-7)*4(0.017^2-0.004^2)\textup{}}{2\pi*0.017(0.025^2-0.004^2)\textup{}}`

or

B = 2.1 × 10⁻⁵ T