Example of Ohm Law

Now that we know how to draw a circuit, let's figure out what is happening in a simple one resistor, one battery (voltage source) circuit.

Example 1 - How much current will flow in a circuit with a 6 V source and a 3 Ω resistance?

V = 6V

R = 3 Ω

I = V/R

I = 6V / 3 Ω = 2 A

To be able to handle increasingly complex circuits, first we have to figure out how two resistors can work together. There are two basic configurations possible: series and parallel. Two resistors are in series when there is only one path for the current to flow through. Two resistors are in parallel when there is one path for current through each resistor, giving a total of two paths.

One way to look at how resistors effect the flow of current is to think of them as zigzag pipes slowing down water flow. If water hits one section like this after the other, the effect of each section slowing the water is added: