Electrical Power

Power in general means the ability to to transform a certain energy in a certain amount of time.
The symbol for power is P. Electrical power P can be calculated as the quotient of transformed energy E and the amount of time t that is needed for the tranformation:

example 1: a car has a higher power than a bike: the car is able to transform much more energy than the rider of a bike in the same period of time.

example 2: a sprinter has a higher power during the race compared with a marathon runner. Sprinters in a race transform a lot more energy than marathon runners over the same period of time. Because the marathon runner transforms less energy per time, his energy reserves last longer, he has more stamina.

example 3: a 60 watts light bulb has a higher light power than a light bulb of 40 watts: per time the 60 watts light bulb transforms more electrical energy into light energy than the 40 watts light bulb.
That's why the 60 watts bulb shines brighter than the 40 watts bulb under the same circumstances.

Electrical power can be calculated using the formula E = U ⋅ I ⋅ t. If this formula is combined with the equation for electrical power, we'll get the following

If time t is cancelled, we'll get this:

In this equation you can see that electrical power depends on amperage and voltage. The resulting power is higher if amperage, that is the amount of charge carriers per time, increases and voltage remains the same. But the same is true if voltage rises and amperage remains the same - then electrical power also increases.

The unit for electrical power is watt (W) which is defined like this:
1 watt = 1 volt ⋅ 1 ampere
In words: in order to achieve electrical power of 1 watt, an electric current of one ampere must flow at a voltage of one volt.