A magnetic circuit has a 20 cm lenght core with a permeability of 0.005 Wb/(Atm). The coil has 250 turns, and draws 0.4 ampere. Determine the mmf of the coil and its magnetic field strength.

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The magnetomotive force of a coil, F, is obtained by multiplying the number of turns with the current strength.

`F = N*I`

Here, `N = 250, I = 0.4` amperes

So, `F= 250*0.4 = 100`

Magnetic field strength, H, is given by:

`H=(N*I)/l` (where, l is the path length)

Plugging in the values,

`H=100/(20*10^-2) = 500 `

Therefore, the mmf of the coil is 100 ampere-turns, and its magnetic field strength is 500 ampere-turns/meter.

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