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Q4. A relay coil has a resistance of 200 Ω and the current required to operate the relay is 150 mA.

When the coil is connected to 50 V d.c. it takes 40 ms to operate. Calculate EACH of the following:

(a) The steady state relay current;

(b) The time constant for the coil;

(c) The inductance of the coil.

(d) To increase the operating time of the relay, a 50 Ω resistor is connected in series with the coil.

Calculate the new operating time for the relay.