A hot wire ammeter reads 10 A in an a.c. circuit. The peak value of current is
10/√2 A
20/π A
5 π A
10 √2 A
A coil of inductive reactance 31 Ω has a resistance of 8 Ω. It is placed in series with the condenser of capacitative reactance 25 Ω. The combination is connected to an AC source of 110 V. The power factor of the circuit is
An alternating voltage V = 200√2 sin (100t) is connected to a 1μF capacitor through an AC ammeter. The reading of the ammeter shall be
10 mA
20 mA
40 mA
80 mA
Hot wire ammeters are used for measuring
a.c. only
d.c. only
Both a.c. and dc
None of these
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
The inductive reactance of a coil of 0.2 H inductance at a frequency of 60 Hz is
75.4 Ω
7.54 Ω
0.754 Ω
7.54 × 10-3 Ω
The reactance of a capacitor of capacitance C is X. If both the freqauency and capacitance be doubled, then new reactance will be
A L-C circuit is in a state of resonance. If C = 0.1 μF and L = 0.25 H, then neglecting the ohmic resistance of the circuit, find the frequency of oscillations.
1007 Hz
100 Hz
109 Hz
500 Hz
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
A 1.0 μF capacitor is charged to 50v. The charging battery is disconnected and a 10mH coil is connectd across the condenser, so that L-C oscillations occur. The maximum current in the circuit (R = 0) is
