Question

A coil of inductance 0.50 H and resistance  is connected to a 240 V-50 Hz a.c. supply. What are the maximum current in the coil and the time lag between voltage maximum and current maximum?

Solution

Correct option is

3.2 ms

The maximum (peak) current in an L-R circuit is given by

               .  

   

  

              

            

In L-R circuit, the current lags behind the voltage by a phase angle , where  

              

Putting the value of  and R, we have 

              

   

The time tag is given by 

                  

                       

                     .

SIMILAR QUESTIONS

Q1

An a.c. generator consists of a coil of 50 turns and area 2.5 m2 rotating at an angular speed of 60 rad s–1 in a uniform magnetic field of 0.30 T. The resistance of the circuit including that of the coil is 500 . Find the maximum current drawn from the generator.    

Q2

In a dynamo, a coil of area 0.2 m2 and having 100 turns rotates in a magnetic field of 0.1 Wb m–2 with an angular velocity of 100 rad s–1. The output terminals are connected through a resistance of . Calculate the torque , as a function of time t, required to keep the coil rotating.

Q3

The electric main in a house is marked 220V-50Hz. Write down the equation for instantaneous voltage.

Q4

A sinusoidal voltage V = 200 sin 314t is applied to a  resistor. Find the frequency of the supply.

Q5

In an a.c. circuit the peak voltage of supply is 300 V. What is rms voltage? What is mean voltage during a positive half-cycle and for a complete cycle?

Q6

 resistor is connected to 220 V-50 Hz a.c. supply. Find rms value of current in the circuit and the net power consumed for a complete cycle.

Q7

A 220 V-50 Hz a.c. supply is applied to a 44-mH inductor. What is rmscurrent in the circuit? What is the net power absorbed over a complete cycle?

Q8

A 110 V-60 Hz a.c. supply is applied to a  capacitor. What is rms current in the circuit? What is the net power absorbed over a complete cycle?

Q9

An alternating voltage E = 200 sin 300t is applied across a series combination of  and L = 800 mH. Calculate the impedance of the circuit.

Q10

An emf E = 100 sin 314t volt is applied across a pure capacitor of 637 . Find the instantaneous current i.