Ohms Law

One of the most useful sets of electrical formulas I can provide for you is the Ohms law formulas. The Ohms law formulas allow you to calculate the Amperage, Voltage, Resistance and Wattage of any electrical circuit. Everyone who builds and works with electronic devices should know these formulas.
For example: suppose you have a 120 volt, 500 watt, projector lamp and you want to know how much amperage it will draw. Looking at inner circle on the the chart below you can see that Watts = P, Volts = E and Amps = I. Since you want to know Amps the formula you need will be in the lower right quarter circle. Just look for the formula that uses P and E.
I = P \ E
Amps = Watts \ Voltage
To find the answer you divide 500 by 120 to get 4.26 amps.
The five calculators above are here to help light artists with the creation of their installations. If you use the above calculators for any reason you assume the risk of all loss, damage, and liability. Always have a licensed electrical engineer assist you with your electrical designs. Always have a qualified optical engineer assist you with your optical designs.

Peace in the Colors
If you are interested in optical design you should first read "The Handbook of Optics IV". It is not an inexpensive book but it is worth every penny if you are going to design your own lens systems.