Changes

Based on what you’ve just seen, the three quantities of electricity which we introduced earlier - voltage, current, and resistance - are clearly tied together somehow. It turns out that they’re actually mathematically related - and that relation is very easy! The equation, called '''Ohm’s Law''', will be one of the most important tools in your toolkit:

'''V''' is the variable for voltage, '''I''' is for current, and '''R''' is for resistance. If you know two of the variables, you can solve for the third! Let’s do a simple calculation. We actually know the total ''V'' for the system: 9V. The LDRs you are using have a minimum resistance of 3kΩ, so we also know ''R''! All we need to do is solve for ''I''.