# When an alternating voltage of 220V is applied across a device X, a current of 0.5Aflows through the circuit and is in phase with the applied voltage. When the samevoltage is applied across another device Y the same current flows through thecircuit but it leads the applied voltage by /2 rad.(a) Name the devices X and Y.(b) Calculate the current flowing in the circuit when same voltage is applied acrossthe series combinations of X and Y.

All the above terms/symbols used below have their standard meaning according to NCERT text.
v = 220 V
I = 0.5 A
1) X is resistor, Y is Capacitor
2) R = Xc as the same current is flowing in both cases.
When connected in series, net impedance= Z =
voltage applied is same
so current is : V/Z =220/622.25 = 0.35355 Ampere

• 33

oh tats not my correct answer

• -6

(1) X - resistor and Y - capacitor

(2) Current = V/Z .

Z = (R2 + XC2)1/2

XC = R = V/i = 220/0.5 = 440 ohms.

So Z = 440 * 21/2

Hence current flowing through the series combination = 220 / (440 * 21/2) = 1/2.828 = 0.353 Amps

• 11
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