
#1
Jan1912, 07:55 AM

P: 3

1. The problem statement, all variables and given/known data
Two charges q = 4.0μ C are fixed in space a distance d = 4.0 cm apart, as shown in the figure. With V = 0 at infinity, what is the electric potential at point C? You bring a third charge q = 4.0μC from infinity to C. How much work must you do? What is the potential energy U of the threecharge configuration when the third charge is in place? Diagram shows (let me use xy coordinate terms to describe this). Charge q at the origin. Another charge q at (4 cm, 0 cm) and point C at (2 cm, 2 cm) 2. Relevant equations Electric Potential = kQ/r 3. The attempt at a solution That's the right equation for the first part correct? I get 1.27*10^4 for the electric potential for one of the charges on point C. When you double that, you get 2.5 * 10^4 V and that should be the answer? (online homework system says that it is wrong). What am I doing wrong here? Also I don't understand the second part. If you are moving a charge from infinity, how can you calculate the work? You don't know the distance? 



#2
Jan1912, 08:15 AM

Emeritus
Sci Advisor
HW Helper
PF Gold
P: 7,416

I see that this is your 2nd post & that you posted your first thread yesterday? I hope DocAl's explanation was helpful, and that you were you able to solve your problem. As for this thread: 4 cm = 4× 10^{2} m, not 4× 10^{+2} m.Your answer is in error by some power of 10. 


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