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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?
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Solution
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, μr = 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.
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