Resistive Loads

In AC and DC circuits containing purely resistive loads, like lights and heaters, Ohm's Law can be used to compute current, voltage and resistance in the circuit. In a resistive circuit Ohm's Law states that voltage is equal to current times resistance. For example, a current of 2 amps flowing through a resistance of 3 ohms is said to produce a voltage "across" that resistance of 6 volts. In other words, Ohm's law shows the relationships between all three variables; voltage, current and resistance. Current will be equal to voltage divided by resistance, and resistance is equivalent to voltage divided by current.

Example:

A wire with a resistance of 10 ohm's is connected to a 9-volt battery. To determine the current flow in the wire, use Ohm's Law and divide 9 volts by 10 ohm's. The current flow in the wire equals 0.9 amps. Replace the 9-volt battery with a 1.5 volt battery. Using the same wire the calculated current flow is 1.5 volts divided by 10 ohm's, which produces a current flow of 0.15 amps. The larger voltage results in more pressure to force more current through the given resistance of 10 ohms.
9 volt = I (amps) x 10 ohms
I (amps) = 9 volt / 10 ohms = 0.9 amps
Replace 9-volt to 1.5 volt battery
I (amps) = 1.5 volt / 10 ohm's = 0.15 amps

Ohm's Law and Other Useful Formula
Resistive Loads