An AC supply gives 30 Vrms which passes through a 10 Ω resistance. The power dissipated in it is
90 √2 W
90 W
45√2 W
45 W
Energy needed to establish an alternating current I in a coil of self inductance L is
L di/dt
zero
LI2/2
IL2/2
A 20 V a.c. is applied to a circuit consisting of resistance and a coil of negligible resistance. If the voltage across resistance is 12V,then voltage across the coil is
10 V
8 V
6 V
16 V
The effective value of an alternating current is 5A. The current passes through 24 Ω resistor. The maximum potential difference across the resistor is
170 V
17 V
1700 V
In an AC circuit with voltage V and current i the power dissipated is
Depends on the phase between V and i
1/√2 Vi
½ Vi
Vi
An alternating voltage E = 220√2 sin 100 t is connected to 1μF capacitor through an a.c. ammeter. The reading of the ammeter shall be
22 mA
10 mA
40 mA
80 mA
In an a.c. circuit, the current is i = 5 sin (100t -π/2) amp and the a.c. voltage is v = 200 sin (100 t) volts. Then power consumption is
200 W
0 W
40 W
1000 W
A lamp consumes only 25% of peak power in an a.c. circuit. What is the phase difference between the applied voltage and the circuit current?
π/6
π/2
π/3
π/4
An a.c. circuit having an inductor and a resistor in series draws a power of 560 W from an a.c. source marked 210 V, 60 Hz. If power factor of the circuit is 0.8, then impedance of the circuit is
103 Ω
63 Ω
12 Ω
114 Ω
