[sdiy] Newbie Electronics Math problem (I need help!)

[Veronica Merryfield]

I'm tempted to say 25 x 10^-3 farads is the value of the voltage  
source but I think the question is missing something about time (J/s  
for instance).


On 2009-09-07, at 8:47 PM, Sam Ecoff wrote:

> Hi All,
>
> I'm attempting to solve a problem for my electronics class. I have  
> the permission of the professor to ask for help, so here I am... I  
> have put about an hour and a half into this, attempting to solve it  
> myself, researching it on the internet, but I am stumped. The  
> problem is from Page 41 of Electronic Technology Fundamentals 3rd  
> ed. by Paynter and Boydell. It reads as follows:
>
> 18. The current through a wire is equal to 100mA. The energy being  
> used by the voltage source is 2.5 x 10^-3 J. What is the value of  
> the voltage source?
>
> I understand that 1 Amp = 1 Coulomb per second, but given that they  
> don't give an amount of time, that formula is not particularly  
> helpful. I also get that 1V = 1Joule/Coulomb. I feel that without  
> specifying a time period, the problem doesn't provide enough info to  
> answer the question.
>
> What am I missing here?
>
> Sam E.
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