RESISTORS CONNECTED IN PARALLEL

 If resistors are connected together between two points as shown in the above circuit diagram, then the resistors are said to be connected in parallel.

TOTAL EFFECTIVE RESISTANCES OF RESISTORS CONNECTED IN PARALLEL 

If resistors R₁,R₂ and R₃ are connected in parallel to a circuit with current ‘I’ and potential difference ’V’ . The total current(I) across combination of resistors in parallel is equal to sum of current across each branch of resistors in the circuit, that is

I = I₁ + I₂ + I₃   —(1)

( I₁ is voltage across R₁, I₂ is voltage across R₂, I₃ is voltage across R₃. But potential difference V is same across all resistors)

According to OHMS LAW 

I = V/R

Apply this to equation (1)

Then

V/R = V/R₁ + V/R₂ + V/R₃

Divid this whole equation with ‘V’ then

1/R = 1/R₁ + 1/R₂ + 1/R₃

So the effective resistance of resistors connected in parallel is

1/R = 1/R₁ + 1/R₂ + 1/R₃