Serie Circuits

If connecting various electrical components such as resistors, so that the current flowing through them all is the same, are said to constitute a series circuit components.

The current intensity I causes a potential difference across the terminals of each resistor coming given it by Ohm's law. That is:

V1 = R1 I                          V2 = R2 I                                 V3 = R3 I

It is evident that the sum of these voltages is equal to the EMF of the battery is:

V = V1 + V2 + V3

So therefore:

V = IR1 + IR2 + IR3 = I (R1 + R2 + R3)

Thus, the intensity of the current flowing through a series circuit is:

I = V / (R1 + R2 + R3 ) = V / Req

Obviously, the equivalent resistance of any number of resistors connected in series is equal to the sum of individual resistors. As regards intensity, the circuit of the attached figure which contains the unique resistance Req is equivalent to the first circuit having three resistors.