Ohm’s Law - It’s not what you think

Let’s quickly revise what you’ll find in most books and websites about Ohm’s Law:

V is potential difference (in volts, V)

I is current (in amperes, A) - I used to stand for electrical Intensity

R is resistance in (ohms, Ω) - Ω is a Greek uppercase letter ‘omega’ - the equivalent of a letter ‘o’ - ‘o’ for ohms

The most basic problem involves a simple circuit where you’re given two of these values and have to find the third.

For example in this circuit

The ammeter reads 2 amperes. The resistance of the bulb is 10 ohms.

What is the reading on the voltmeter?

We use

V = IR

V = 2 x 10

V = 20 volts

If we needed to find current or resistance, then we can use a triangle to work out how to find the unknown.