Ohm's law

Here, I will explain how to calculate the current by two types:
 - Ohm's law:

Here's the Ohm's law, I is the current (amperes), then V is the voltage (volts) and R is the resistance (ohms).

If you would know the value of the current of your circuit, you only need to calculate through Ohm's law.

Example:

 You have a circuit connected with 20 volts and two resistors in series with 1 Kiloohm each. How much is the current?

  - Multimeter:

You also can measure the current of a circuit with the multimeter. You have to put the roulete in the section of Amperes and it's like measuring voltage.