Answer to Question #122631 in Electrical Engineering for Varun Bhutada

Question

An air-gap between two pole pieces is 20 mm in length and the area of the flux path across the gap is 5 cm2. If the flux required in the air-gap is 0.75 mWb. Find the mmf necessary.

Answer 1

Given

An air-gap between two pole pieces is 20 mm in length ,

A = 5 cm² which is 5*10^-4 m²

Air gap then = 0.75 mwb = 0.75*10^-3

Solution

we know that B = u_oH

m.m.f = H*L

but H = (alpha/Au_o) * L and U_o = 4*3.14*10^-7

=(0.75*10^-3* 20*10^-3)/(5*10^-4 * 4 *3.14 * 10^-7)

= 0.238*10⁵ A

Therefore m.m.f = 23870 A