Page 414 - Basic Electrical Engineering

Figure 3.76

[Ans 20.4 V]

42. A resistance of 50 Ω, an inductance of 0.1 H, and a capacitance of 50 mf are connected in
series across a 230 V, 50 Hz supply. Calculate (i) the value of impedance; (ii) current flowing;
(iii) power factor; (iv) power consumed.

[Ans Z = 59.5 Ω, I = 3.86 A, P.f. = 0.84 leading; P = 746.7 W]

43. In an R–L–C series circuit, the voltage across R is 160 V, across L is 240 V, and power
consumed is 1000 W when a voltage of 200 V at 50 Hz is applied across the circuit. Calculate
the value of the capacitor and the current flowing through the circuit.

[Ans C = 165.8 μF, 6.25 A]

44. A impedance of Z = 50 ∠− 60° Ω is connected across a 230 V, 50 Hz supply. Calculate the
values of circuit elements, current, and power factor.

[Ans R = 25, C = 73.54 μF, I = 4.6, P.f. = 0.5 leading]

45. A coil of resistance 5 Ω and inductance 20 mH is connected across a voltage of v = 230 sin
314t. Write an expression for the current flowing through the circuit.

[Ans i = 28.75 sin (314t - 51°]

46. A resistance of 50 Ω and a capacitor of 100 mf are connected in series. The supply voltage to
the circuit is 200 V at 50 Hz. Calculate the voltage across the resistor and across the capacitor.
Also calculate current and power factor.

[Ans V = 168.7 V, V = 107 V, I = 3.37 A, P.f. = 0.84 leading]
C
R

47. In an R–L–C series circuit a maximum current of 0.5 A is obtained by varying the value of
inductance L. The supply voltage is fixed at 230 V, 50 Hz. When maximum current flows
through the circuit, the voltage measured across the capacitor is 350 V. What are the values of
the circuit parameters?