A sinusoidal alternating current is represented by;
I = I0 sinωt where I0 is the peak value
The current varies like a sine wave so it is called sinusoidal.
The magnitude of the power dissipated in a resistor is given by the expression:
I2R or VI or V2/R
The current and voltage is represented by;
I = I0 sinωt
V = V0 sinωt
And the peak value is I0 and V0.
The power generated in the resistance R is given by the usual Formula
P = I2R
But current I must be written as;
I = I0 sinωt
P = I2R sin2ωt
Since I0 and R are constant so;
= ½ V02/R = ½ I02R
Root mean squared values
Average value of the square of current or voltage is given as;
<I2> = ½ I02
<V2> = ½ V02
The root mean square value of alternating current is that steady current which delivers the same average power as the a.c. to resistive load.
A transformer is a device used to change the voltage of a circuit using electromagnetic induction. It consists of a soft iron core wrapped on both side with wire. The first coil of wire is called primary coil and the other coil is secondary coil.
A current flows through the primary coil which creates magnetic field which cuts through the turns of wire on the secondary coil. This induces the e.m.f. and current in second coil.
- Step Up transformer
Where Vs> Vp or Ns > Np
- Step down transformer
Where Vp > Vs or Ns < Np
In both cases
NS/NP = VS/VP = IP/IS
It is the process of converting alternating current a.c. into direct current d.c.
Full wave rectification involves four diodes and is referred to as a bridge rectifier circuit. Diodes are used to convert a.c. to d.c. A single diode gives half-wave rectification. A bridge of four diodes gives full-wave rectification. A capacitor soothes the rectified voltage.