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


Correct option is

20 cos 314t


In a pure capacitor the current leads the voltage by 90o. Therefore, the instantaneous current is given by  






Substituting this value of i0 in eq. (i), we get  




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.


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


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


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?


 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.


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?


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?


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


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?


An a.c. voltage V = 200 sin 314t is applied across a series C-R circuit.Where . Find the capacitive reactance.