4.07 Resistors in parallel.

Parallel circuits.

Resistors in parallel.

The diagram below shows three resistors connected in parallel. To show how to calculate the total resistance, we will use Kirchhoff's current law and ohms law.

resistors in parallel

According to Kirchoff's current law, the sum of the currents flowing out of the junction (and through each resistor), is equal to the current flowing into the junction.

According to Ohm's law,    I = V/R.     Therefore substituting for I gives;

dividing both sides of the equation by V, gives;

Therefore to calculate the total resistance of resistors in parallel;
1/RT = 1/R1+ 1/R2 + 1/R3.