(1) *Voltage in a Parallel Circuit.*

You have seen that the source

voltage in a series circuit divides proportionally across each resistor in

the circuit. In a parallel circuit, the same voltage is present in every

branch.

A branch is a section of a circuit that has a complete path for

current. In figure 42 on the previous page, this voltage is equal to the

applied voltage (Es). This can be expressed in equation form as:

Es = ER1 = ER2

Voltage measurements taken across the resistors of a parallel circuit, as

illustrated by figure 43, verify this equation.

Each meter indicates the

same amount of voltage. Notice that the voltage across each resistor is the

same as the applied voltage.

FIGURE 43.

VOLTAGE COMPARISON IN A PARALLEL CIRCUIT.

Example: Assume that the current through a resistor of a parallel circuit is

known to he a 4.5 milliamperes (4.5 mA) and the value of the resistor 30,000

Ohms. Determine the source voltage. The circuit is shown in figure 44 on

the following page.

Given:

R2 = 30,000 Ohms

IR2 = 4.5 milliAmps