Energy measurements?

Question

i was changing my light bulb for one of the cfl ones and i was wondering how much energy does a light bulb take over time

Heres the information for it

23w

120v

60hz

380mA

so how do you convert this over time

so is it like 23w every sec,minutes,hours

whats mA stand for to?

Answer 1

I'll focus on the 23w for your example. So it helps to describe the difference between power (watts) and energy (watt-hours). Watts are a measure of how fast something uses energy (kinda like miles-per-hour in a car). Electrical energy is measured in watt-hours (kinda like total distance traveled in a car in miles).

So, if you have your example light bulb on for one hour the speed that it uses energy is 23watts while it is on. The speed that it is using energy when it is off is zero watts. The total energy it uses when it is on over one hour is 23watt-hours. If it is on for two hours it has used 46watt-hours (23watts times 2 hours = 46 watt-hours).

The electric company charges you for each 1000watt-hours that you use (called 1 kilowatt-hour where kilo means 1000). An electric company might charge in the neighborhood of a dime for each kilowatt-hour of energy that is used. So for your 23w light to cost 1 dime (at the example price) it would have to be "on" for more than 43hours. (i.e. 10000watt-hours/23watts = 43.4 hours)

Of course your own electric company might be charging a bit more or a bit less for each kilowatt-hour of energy, but that is the general idea.

Answer 2

P=E x I Power =Voltage (E) x current or flow (I) that is your wattage. It's a multiplication of the voltage of the source x the amperage the load draws. Mulitply this by an industry standard length of time and you get your energy consumption / time unit. Usually watt-hours. 1000 watt-hours is one kilowatt-hour KWh, which is what your electric utility bill measures it in.

mA is a measure of small current or flow, and is equal to 1/1000 of an Ampere or Amp. In the "more than you wanted to know" category, an Ampere is a flow rate of one "Coulomb" / sec of electrons across any  given point in a wire. A "coulomb" is equal to Avagadro's # of electrons which = 6.02 x 10-23 power of the little buggers.