# I need help with this electricty problem

I need help with this electricty problem:(

## Homework Statement

At the end of a long day, your instructor finally sits down to write your final examination, after making a cup of coffee he goes into his office, turns on the five, 40-Watt lights, and starts writing.

How much current is flowing through the circuit in your instructor’ office?

How many electrons are moving from the power company into your instructors’ home in order to continually generate the current in his office circuit?

## Homework Equations

I can't find a formula to use to find current with just watts given.

## The Attempt at a Solution

Well, should we suppose the voltage is 120V or 230V (or something else)? Then you can figure out the electricity from the power equation for resistors (the tungsten thread in the lightbulb is essentially a resistor).

so 40W/230V=.179A?

would the .179 be multiplied by 5 because there are 5 lights?

Interesting question, what do you think? Say they are hooked up on individual circuits--answer seems obvious. What about if they were hooked up in series like ole fashioned Xmas tree lights?

EDIT: BTW, unless you're in Europe, odds are the voltage is 120 or 110.

so it is 5* .173?

so it is 5* .173?

sure if you use 230V.