Ohm's law

Electronics is all related to Ohm's law. This provides the relation between voltage, current, and resistance in a circuit. The law states that the current passing through a resistor is directly proportional to the applied voltage across it. In mathematical forms, it looks like this:

A simple way to remember and apply it according to either of the variables is the following triangle:

If we want to find the current, we cover I and we get V divided by R. The same goes for R: we cover it and we obtain V divided by I. Lastly, V will equal I multiplied with R. Let's now apply this knowledge to the following circuit:

Here, we have one 5-volt voltage source in series with one resistor R1 with a resistance of 100 Ω. Because we have only one resistor, the total voltage across it will be equal to the voltage of the source, 5 V. We can now apply Ohm's law to find the current in the circuit:

Remember that 1 ampere equals 1,000 milliamperes, represented by the unit mA...