# Question I hope you can help

1. Aug 26, 2006

### lespaul5895

Right now I'm a first year electrical engineering student at Purdue University. I have a problem that I have to do for a homework assignment I read the entire chapter and cannot find out how to do this problem. Any help would be appreciated, if this isn't the right place to ask this question just let me know and if not I would appreciate any information on how I could find help.

A 100 watt light bulb dissipates 100 joules of energy per coulomb of charge. Find its voltage drop.

2. Aug 26, 2006

### Astronuc

Staff Emeritus
3. Aug 27, 2006

### lespaul5895

call me dense but I don't see the relationship there, I don't see how those equations relate to the problem given. Most of those deal with current and resistance, please explain. sorry I'm kinda slow when it comes to learning stuff and I want to make sure I fully understand this.

edit: So what you're saying is that 1Watt = J/C? so the equation would read 100w = 100J/1C = 100V?

Last edited: Aug 27, 2006
4. Aug 27, 2006

### Astronuc

Staff Emeritus
I was showing that 1 V = 1 J/C and so 100 V = 100 J/C.

Now, 1 W = 1 J/s, and if 100 W dissipates 100 J/C, that implies (100 W)/(100 J/C) = (100 J/s)/(100 J/C) = 1 C/s = 1 A.

So for a 100 W light bulb to dissipate 100 J/C, the voltage drop is 100 V, and the current is 1 A.