Question

A magnetic circuit has an iron length of 100 cm and air gap length 10 cm. If μr = 200 then which of the following is true?

(a) Mmf for iron and air gap are equal

(b) Mmf for iron is much less than that for air gap

(c) Mmf for iron is much more than that for air gap

(d) Mmf for iron and air gap are not equal

I had been asked this question during an internship interview.

Asked question is from Series-Parallel Interconnection of Two Port Network in division Two-Port Networks of Network Theory

Answer 1

The correct choice is (a) Mmf for iron and air gap are equal

For explanation: We know that, MMF for air = \(\frac{B}{4π X 10^{-7}}\) X 10

Where B is the magnetic field intensity.

Also, MMF for iron = \(\frac{B X 100}{200(4π X 10^{-7})}\)

= \(\frac{B X 0.5}{4π X 10^{-7}}\).