An Ohm's Law calculator is used to substitute values into an equation that compares voltage to resistance to determine electrical current. On a DC circuit, it is a straightforward ratio, but even with AC, it can be used for an approximation. Ohm's Law can also help determine power consumption.
Voltage is the amount of electrical pressure, or the difference in potential. Resistance is the force preventing electrical flow. Current is the resulting flow of electricity; Ohm's Law states that one ampere is the amount of current resulting from a charge of one volt applied across one ohm of resistance. Changing one quantity affects the others on the circuit.
One way to use Ohm's Law is to determine how much power a given appliance is using. Electrical power, expressed in watts, is the product of voltage and current, so it's necessary to know current or to possess an ohmmeter. Using the ohmmeter, individuals can check resistance in the appliance per the meter's user instructions by dividing the household voltage, or 120 in America, by that figure to determine current, and then multiplying current by voltage. For example, an appliance that measures 60 ohms of resistance draws 2 amperes of current and uses 240 watts of power per second.