# Electronic – can somebody give an analogy of what an ampere is

electromagnetism

I'm trying to understand the difference between amperes and watts. I have a string of LEDs that say require 5W of power and 5amps. What's a good way to memorize the difference and significance of these two values?

#### Best Answer

Well, the definition of an ampere is quite figurative: It is the current through two parallel infinitely long and thin wires, that are 1 metre apart from each other, so that the force between them is exactly \$2 \cdot 10^{-7}\$ Newton per metre (thanks to @rioraxe for checking the numbers).

Admittedly, this is not easy to transfer to reality. In fact, it is very hard to give another example. It is easier, when you think in power, rather than current. At 5 V, you get 5 Watts. At 230 V you get 230 W at 1 A.

Concerning your case with LEDs at 5V, you need to take light efficiency into account. LEDs have around 80 to 120 Lumens per Watt. So if you have 25 watts in LEDs, you can think of around 2500 Lumens, which is around as much as two Lightbulbs with 100 Watts have.