Determine the value of produced mmf (in Amp-turns) in a coil if the coil has a 120 turns carrying a current of 0.1 A

• A. 12
• B. 14
• C. 16
• D. 18

Answer: (A)

Magnetomotive force (mmf): It is defined as the force that drives magnetic flux throng the magnetic circuit. In all practical magnetic circuits, this is provided using a current-carrying winding (coil), and is the product of the current and the number of turns in the winding. Its SI unit of measurement is the ampere.
m.m.f Fm = N.I Ampere-turn
where N is the number of conductors (or turns) and I is the current in amperes. The unit of mmf is sometimes expressed as ‘ampere-turns’. However, since ‘turns’ have no dimensions, the Sl unit of mmf is the amp.
Given
Number of turns N = 120 turns
Current I = 0.1
Fm = 120 × 0.1
Fm = 12