# Combination of Resistors

Chapter-3|Current Electricity| NCERT 12th Physics:

Combination of Resistors:

Resistors in Series:

Resistors are said to be connected in series, If the same current is flowing through each resistor, when different potential difference is applied across the combination.

Let three resistors having resistance R₁, R₂ and R₃ respectively are connected in series, let V be the potential difference applied across A and B using the battery E and same current I is passing through each resistor. If V₁, V₂ and V₃ be potential difference across R₁, R₂ and R₃ respectively.

Then according to Ohm’s law, we know that

V= IR

Thus, equivalent resistance of a number of resistors connected in series is equal to the sum of individual registers.

Resistors in Parallel:

Resistors are said to be connected in parallel if the potential difference across each resistor is same and sum of individual current applied to each resistance is equal to the total current from the battery.

Let three resistors having resistance R₁, R₂ and R₃ respectively are connected in parallel. let V be the potential difference applied across A and B using the battery E and I be the main current in the circuit from battery. If I₁, I₂ and I₃ are currents through the three resistances R₁, R₂ and R₃ respectively, then current