## Physics XII Content

# Combination of Resistors

**Series Combination**

If resistors are connected end to end such that same current flows in each resistor but different potential difference is observed across then such combination is called series combination.

Resistors in series |

Let, R_{1}, R_{2} and R_{3}be the three resistors connected in series to a battery of volt V. Same current I flows in each resistors while V_{1}, V_{2} and V_{3}potential drops are observed across R_{1}, R_{2} and R_{3}respectively.

**Parallel Combination**

If one of the ends of resistors are connected to a common point and the rest of the ends to another common point such that same potential difference is observed across each resistor but different current in each resistor than such combination is called parallel combination.

Resistors in parallel |

Let, R_{1}, R_{2} and R_{3}be the three resistors connected in parallel to a battery of volt V. Current I_{1}, I_{2} and I_{3} flows across resistance R_{1}, R_{2}and R_{3} while potential drops V is observed across each resistor. Then,

**Some Rules**

_{eq}= nR” so we get maximum resistance from the given resistors when we connect them in series.

ii. If two identical resistors each of resistance R are connected in parallel then,

_{1}and R

_{2}are connected in parallel then,

iv. If two resistors one big and next small are connected in parallel then,

v. The ratio of maximum resistance to the minimum resistance obtained by connecting n identical resistors in series and in parallel is n^{2</sup >.}