Ohm’s Law is the mathematical relationship between Voltage, Current and Resistance in a circuit.
E=IR Voltage “E” equals Current “I” times Resistance “R”.
In Low Voltage electronics, this is used primarily to determine voltage drop in wire runs between a power source and a remote appliance.
Sample: The electrical resistance of a wire run is determined by wire gauge and distance. Published charts are available on the internet. The current of a device is supplied by the device’s manufacturer.
The calculated wire resistance is multiplied by the device current to yield a voltage value. This voltage is called the Voltage Drop. This voltage drop is subtracted from the applied voltage and the result must be within the operational specifications for the device on the circuit