Question

A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 1.2 A?

Answer 1

Mean radius of a Rowland ring, r = 15 cm = 0.15 m

Number of turns on a ferromagnetic core, N = 3500

Relative permeability of the core material, μ_r = 800

Magnetising current, I = 1.2 A

The magnetic field is given by the relation:

B = `(μ_"r"μ_0"IN")/(2π"r")`

Where,

μ₀ = Permeability of free space = 4π × 10⁻⁷ T mA⁻¹

B = `(800 xx 4π xx 10^-7 xx 1.2 xx 3500)/(2π xx 0.15)`

= 4.48 T

Therefore, the magnetic field in the core is 4.48 T.