Question

A virtual current of 4 A flows in a coil when it is connected in a circuit having a.c. of frequency 50 Hz. The power consumed in the coil is 240 W. Calculate the inductance of the coil if the virtual p.d. across it is 100 V. 

Solution

Correct option is

0.0637 H

Let L be the inductance, R the resistance and Z the impedance of the coil. The power is consumed in R only. Thus, the average power is

              

   

  

   

  

Here,   

           

SIMILAR QUESTIONS

Q1

An inductor L, a capacitor of  and the resistor of  are connected in series with an a.c. source of frequency 50 Hz. If the current is in phase with the voltage, calculate the inductance of the inductor.

Q2

A capacitor, a  resistor and a 80-mH inductor are in series with a 50-Hz a.c source. Calculate the capacitance if the current is in phase with the voltage. 

Q3

A series L-C circuit has L = 0.405 H and . The resistance R is zero. Find the frequency of resonance.    

Q4

In a series L-C-R circuit connected to a variable frequency 220-V source; we have : L = 4.0 H, . Calculate the resonant frequency of the circuit.   

Q5

A variable-frequency 230-V alternating voltage source is connected across a series combination of L = 5.0 H,  and . Calculate the angular frequency of the source which drives the circuit in resonance. 

Q6

A series LCR circuit with L = 0.12 H, C = 480 nF and  is connected to a 230-V variable-frequency supply. What is the source frequency for which current a amplitude is maximum? Find this maximum value.

Q7

An L C R circuit has L = 10 mH connected in series to a source of  volt. Calculate the current-amplitude and the average power dissipated per cycle at a frequency 10% lower than the resonant frequency. 

Q8

A 750-Hz, 20-V source is connected to a resistance of , an inductance of 0.1803 H and a capacitance of , all in series. Calculate the time in which the resistance (thermal capacity = 2 JoC–1) will get heated by 10oC. 

Q9

Obtain the resonant frequency and Q-factor of a series LCR circuit with L= 3.0 H. How will you improve the sharpness of resonance of the circuit by reducing its full width at half maximum by a factor of 2?  

Q10

An a.c. circuit having an inductor and a resistor in series draws a power of 560 W from an a.c. source marked 210 V-60 Hz. The power factor of the circuit is 0.8. Calculate the impedance of the circuit and the inductance of the inductor.