Question

A coil consisting of 50 turns of wire is powered by a 9V battery. If the coil draws 1.5 A from the battery, what is the MMF, in ampere-turns ?
A. 75 ampere-turns
B. 300 ampere-turns
C. 59 ampere-turns
D. 450 ampere-turns

Answer 1

A. 75 ampere-turns

Explanation:

Given:

Number of turns, n = 50

Voltage, V = 9V

Current, I = 1.5A

MMF= ?

MMF is magnetomotive force.

MMF is independent on voltage and dependent on the number of turns and current in the wire.

Thus, MMF can be written as:

$MMF = nI$

On substituting the value we get:

MMF = 50 X 1.5

MMF = 75 ampere-turns