![]() That’s what they have based their calculations on. What’s going on? Well manufacturers usually give a ‘nominal’ voltage rating, in this case 12 volts. We can see that the current drawn is less. If we are starting with a fully charged battery, the voltage might be 13.5 Volts, so working it out again for the corrected voltage we get: The reason is it’s highly unlikely that the voltage is exactly 12 volts. If we were to measure the current using our multimeter, we probably wouldn’t get a reading of 5.41 Amps. We know the voltage is 12 volts so using P / V = I we can now work out the current: The rated power for the television found from the manufacturers data is 65 Watts. Lets work out the current for a 12 volt television. (My old Physics teacher told us an easy way to remember them “The Vatican is Roman Catholic” and “The Pope lives in the Vatican and he’s Catholic” – I meaning Current)Īs we usually know two parts of the equation, it’s easy to work out the third. There are a few more and I’ve included a copy of the “Electric Wheel” at the end. You don’t need to know the theory behind the formulas, just remember these two triangles:-Įach triangle shows the three most used formulas that you will need. Resistance – measured in Ohms, Symbol Ω (Omega) If you have little or no electrical background it can get confusing, so hopefully this guide will make it clearer. A basic understanding of how to do this will help when fault-finding or deciding on the correct cable size when adding accessories. ![]() In some of the guides I have included calculations for working out current, resistance etc. A very basic introduction to some simple maths that allow you to work out power, current and resistance.
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