A parallel circuit has two 8.0-ohm resistors and a power source of 9.0 volts. If a 12.5-ohm resistor is added to the circuit in parallel, how will the current be affected and what value will it have?

- - The two 8-ohm resistors in parallel are equivalent to

a single 4-ohm resistor.

- - The current in the circuit is

(voltage) / (resistance) = (9v) / (4ohms) = 2.25 Amperes

- - If another resistor is added in parallel, then no matter how large

or small it is, the current in the circuit increases.

(When another lane is added to a road, the traffic capacity of the

road increases.)

The circuit is now equivalent to a 12.5-ohm resistor in parallel

with 4-ohms. That's ...

(12.5 x 4) / (12.5 + 4) = 50/16.5 = 3.03 ohms.

- - The new current is (9v) / (3.03 ohms) = 2.97 Amperes