Question

The current flowing through a coil of resistance 800 ohm is to be reduced by 80% .What value of shunt should be connected across the coil

Answer 1

resistance of coil, R = 800 ohms

Let resistance of shunt be S.

according to question,The current flowing through a coil of resistance 800 ohm is to be reduced by 80%.

If we assume initially, I current flows through coil, then final amount of current flows through coil is (1 - 0.8)I = 0.2I

shut is connected in parallel combination.

I(RS)/(R + S) = I'R

or, I × 800S/(800 + S) = 0.2I × 800

or, 5S = S + 800

or, 4S = 800

or, S = 200 ohms

hence, resistance of shunt is 200ohms