Question

What's the formula to find out power

Answer 1

In general, 

                 Power = (energy moved) / (time to move the energy) .

If it's mechanical power, then     

                 Power = (work done) / (time to do the work) .

If it's electrical power, then it can be any one of these:

                 Power  =  (volts)  x  (amperes)

                 Power  =  (volts)²  /  (resistance, ohms)

                 Power  =  (amperes)²  x  (resistance, ohms) .

Whatever kind of energy you're dealing with, power always
turns out to be

                  (amount of energy produced, used, or moved)
divided by
                  (time taken to produce, use, or move the energy) .