Ohm's law is one of the most commonly used physics principles. It relates voltage, current and resistance. It can be written as:

V= I x R

It states that the voltage or potential difference across a conductor or between any two points can be determined as the product of current flowing through this conductor (or between the two points) and the resistance offered by the conductor (or all the devices between the two given points).

It can also be written as: I = V/R

and can help us determine the electrical current in a circuit.

A circuit typically has a voltage source, such as a battery, some resistance (offered by the device or wire, etc.). Knowing the voltage generated by the battery and the resistance in the circuit, we can calculate the current flowing through it.

Hope this helps.