Ohm's law states, that the current through a resistor, is directly proportional to the voltage across it. The ratio of the voltage across a component, to the current flowing through it, is defined as resistance.

where

- R = resistance in ohms (Ω).
- V = voltage in volts (V).
- I = current in amps (A).

Resistance restricts the flow of current through a component and converts the electrical energy to heat. Ohm's law can be used to determine current, voltage or resistance in a circuit, if two of the three quantities are already known.

**Example.**

Ohm's law allows us to calculate the current that will flow in a circuit, if we know the voltage that is being applied and
the total resistance of the circuit.

A 12V power supply is connected to a cct. It the cct's resistance is 5 Ohms, how much current will flow through the cct?

- V = 12V.
- I = ?
- R = 5 Ω .

R = V/I, Therefore I = V/R, = 12/5, = 2.4A