A wire of resistance R is connected in series with an inductor of reactance ωL. Then quality factor of RL circuit is
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
In an AC circuit, the rms value of current, irms is related to the peak current, i0 by the relation
irms = √2i0
irms = πi0
irms = i0/π
irms =( 1/√2) i0
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
A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is approximately
30%
50%
90%
10%
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
Energy needed to establish an alternating current I in a coil of self inductance L is
L di/dt
zero
LI2/2
IL2/2
In an LCR series circuit, the capacitance is made one-fourth when in resonance. Then what should be the change in inductance so that the circuit remains in resonance?
4 times
¼ times
8 times
2 times
In an experiment, 200 V AC is applied at the ends of an LCR circuit. The circuit consists of an inductive reactance (XL) = 50 Ω, capacitive reactance (XC) = 50 Ω and ohmic resistance (R) = 10 Ω. The impedance of the circuit is
10 Ω
20 Ω
30 Ω
40 Ω
The effective value of an alternating current is 5 A. The current passes through 24 Ω resistor. The maximum potential difference across the resistor is
170 V
17 V
1700 V
