671. A wire of resistance R is coiled inductively so that its inductance is L. The impedance of the coil at a frequency of f is_______________?
A. (R+2πfL)
B. R+1/2πfL
C. (R2+f2L2)
D. (R2+4π2f2L2)

672. Ammeter connected in an AC circuit measures______________?
A. The exact value of the current
B. RMS value of the current
C. The net value of the current
D. The peak value of the current

673. When a pure inductor of inductance L and a pure capacitor of capacitance C are connected in parallel to a sinusoidal potential difference V the potential difference across both L & C will be_______________?
A. Same
B. Different
C. At L will be more than at C
D. At L will be less than at C

674. What is the self-inductance of a coil in which an induced emf of 2V is set up when the current changes at the rate of 4 As-1 ?
A. 0.5 mH
B. 0.5H
C. 2.0H
D. 8.0H

675. The frequency of a circuit consisting of a capacitance C and a resistor R is________________?
A. C/R
B. R/C
C. 1/RC
D. 1/ 2RC

676. A 10Ω electric heater is connected to a 220V 50Hz mains supply. What is the peak value of the potential difference across the heater element ?
A. 220V
B. 220/ 2V
C. 110V
D. 220 √2V

677. A choke is used as a resistance in_________________?
A. DC circuit
B. AC circuits
C. Both AC and DC circuit
D. Full wave rectifier circuit

678. At resonance the value of the power factor in an L-C-R series circuit is_______________
A. Zero
B. 2
C. 1
D. Not definite

679. An A.C series circuit containing 4Ω resistance and 3Ω inductive reactance. The impedance of the circuit is______________?
A. 1Ω
B. 5Ω
C. 7Ω
D. 7Ω

680. An inductive coil has a resistance of 100Ω. When an AC signal of frequency 1000Hz is fed to the coil the applied voltage leads the current by 45Ω. What is the inductance of the coil ?
A. 10mH
B. 12mH
C. 16mH
D. 20mH

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