What is the power factor of an LCR series circuit at resonance?
With the help of a diagram, explain the principle of a device which changes a low voltage into a high voltage but does not violate the law of conservation of energy.
Give any one reason why the device may not be 100% efficient.
Draw a labelled diagram of a step-up transformer.
Obtain the ratio of secondary to primary voltage in terms of the number of turns and currents in the two coils.
A power transmission line feeds input power at 2200 V to a step-down transformer with its primary windings having 3000 turns. Find the number of turns in the secondary to get the power output at 220 V.
What is the phase difference between the voltage across L and C in a series LCR-circuit connected to an a.c. source?
An a.c. voltage V = Vmsin t is applied across an inductor of inductance L
Apply Kirchhoff's loop rule to obtain expressions for the current flowing in the circuit.
Apply Kirchhoff's loop rule to obtain expressions for the inductive reactance L.
Find the instantaneous power Pi supplied to the inductor.
Show graphically the variation of P with t.
An ac voltage V = V0sin is applied to a pure inductor L. Obtain an expression for the current in the circuit. Prove that the average power supplied to an inductor over one complete cycle is zero.
An a.c. source generating a voltage v = vmsin ωt is connected to a capacitor of capacitance C. Find the expression for the current i, flowing through it.
Plot a graph of v and i versus ωt to show that the current is π/2 ahead of the voltage.
What is capacitive reactance?
An ideal inductor is connected across an AC source of voltage. The current in the circuit
An inductor, a capacitor and a resistor are connected in series across an ac source of voltage. If the frequency of the source is decreased gradually, the reactance of:
A metal detector is based on: