A coil consists of 750 turns and a current of 10 A in the coil gives rise to a magnetic flux of 1200 μWb. What are the inductance of the coil and the average e.m.f. induced in the coil when this current is reversed in 0.01 second respectively?

Concept:

The formula to calculate the inductance L of a coil is

\(L = \frac{{N\phi }}{I}\)

Where

N is the number of turns

ϕ is the magnetic flux

Average induced emf is given by \(E = L\frac{{dI }}{{dt}}\)

Where N is the number of turns

dI is changing in current

dt is changing in time

Calculation:

Given,

N = 750

ϕ = 1200 μWb

t = 0.01 s

I = 10 A

dI/dt = (10-(-10))/0.01 = 2000 A/s

\(L = \frac{{N\phi }}{I} = \frac {750 \times 1200 \times 10^{-6}}{10} = 0.09~ H\)

\(V = L\frac{{dI }}{{dt}} = \frac{0.09\times 10^{-6}\times20 }{0.01} = 180~V\)