(b) *Product Over the Sum Method. * A convenient method for finding

the equivalent, or total, resistance of two parallel resistors is by using

the following formula:

This equation, called the product over the

sum

formula,

is

used

so

frequently it should be committed to memory.

Example: What is the equivalent resistance of a 20 Ohm and a 30 Ohm resistor

connected in parallel, as in figure 52 on the following page.

Given:

R1 = 20 Ohms

R2 = 30 Ohms

(4) *Power in a Parallel Circuit.*

Power computations in a parallel

circuit are essentially the same as those used for the series circuit.

Since power dissipation in resistors consists of heat loss, power

dissipations are additive, regardless of how the resistors are connected in

the circuit. The total power is equal to the sum