First, we will look at the circuit diagram of the resistors in series and as we know that resistors in series have the same amount of current passing through them but the potential difference across each resistor is different.

The potential difference V is equal to the sum of potential differences V₁, V₂, and V₃. That is the total potential difference across a combination of resistors in series is equal to the sum of a potential difference across the individual resistors. That is,

V = V₁+ V₂+ V₃

Let I be the current through the circuit as shown in the above figure.

1. The current through each resistor is I.

2. We can replace these three resistors by an equivalent single resistor of resistance R.

3. The potential difference V and current I should remain the same.

Applying the Ohm’s law to the entire circuit, we have

V = I R

On applying Ohm’s law to the three resistors separately, we further

Have

V₁ = I R₁

V₂ = I R₂

and V₃ = I R₃

I R = I R₁+ I R₂+ I R₃

or

Rs = R₁ +R₂ + R₃

We can conclude that when several resistors are joined in series, the

the resistance of the combination Rs equals the sum of their individual

resistances, R₁, R₂, R₃, and is thus greater than any individual resistance.