Ohm’s Law expresses fundamental relationships among voltage, current, and resistance. On occasion, you may be asked to calculate any one of the three variables in this equation, given the other two. As a result, good mnemonics to remember is the VIR triangle.
VIR triangle for Ohm’s Law (Diagram)
How to use the VIR Triangle for Ohm’s law?
If the two variables you know are across from one another, then multiplying them will get you the third. If you know the current (I) and the resistance (R) in a given circuit, you can calculate the voltage (V) by multiplying the current and the resistance.
If the two variables you know are above and below one another, then you can get the third variable by dividing the one above by the one below. For instance, if you know the voltage and the resistance in a given circuit, you can calculate the current by dividing the voltage by the resistance.