**System of resistors:**

Let’s study some basic examples to study the combination of resistors.

**Resistors in series:**

The equivalent resistance of combination of resistance connected in series is given by,

1) Equivalent resistance , R_{s} = R_{1 }+ R_{2} + R_{3}

**Resistors in parallel:**

The equivalent resistance of combination of resistance connected in parallel is given by,

**Ex. 1) Find the equivalent resistance in following circuit if value of each resistance is 10 Ω**

Solution: Data, R_{1}=10 Ω, R_{2}=10 Ω, R_{3}=10 Ω**, **R_{4}=10 Ω

As we can see in the figure above, resistors R_{2 }& R_{4} are connected in parallel, so their equivalent resistance can be obtain as

*Hence the equivalent resistance of circuit is **.25Ω*

**Ex.** Find the value of current in following circuit.

Solution: Data,

Let R_{1}=10 Ω, R_{2}=20 Ω, R_{3}=20 Ω**, **R_{4}=20 Ω, R_{5}=25 Ω

V= 220 V

To find total current ‘I’, first we need to find total resistance of circuit.

As we can see in diagram, R_{2}, R_{3} and R_{4 }are connected in parallel, then equivalent resistance of this part circuit is say R_{P}

I = V/R

∴ I = 220/41.67

∴I = 5.28 A

Hence 5.28 A current will be flow through the given circuit.