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
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
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
What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10μF and ω = 1000s-1?
100 mH
1 mH
Cannot be calculated unless R is known
10 mH
Hot wire ammeters are used for measuring
a.c. only
d.c. only
Both a.c. and dc
None of these
The time constant of C - R circuit is
1/CR
C/R
CR
R/C
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
10 V
170 V
17 V
1700 V
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
An alternating voltage E = 200 sin 300 t is applied across a series combination of R = 10 Ω and an inductor 800 mH. The power factor of the circuit is
0.022
0.065
0.042
0.084
Energy needed to establish an alternating current I in a coil of self inductance L is
L di/dt
zero
LI2/2
IL2/2
