**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