## point charge attractioning a positive charge from infinity to 30cm

1. The problem statement, all variables and given/known data

A point charge of 2.0 10-9 C is located at the origin. How much work is required to bring a positive charge of 4.0 10-9 C from infinity to the location x = 30.0 cm?

and it requests the answer in J

2. Relevant equations

W=-q2(delta)V

DeltaV = Ke q1/d

where delta v is potential difference, W is work, q2 and q1 are the charges, Ke is coulombs constant, and d is distance

3. The attempt at a solution

I plugged in all of the variables using 4.0 *10 ^ -9 as my q1 and 2.0*10^-9 as my q2 and that was wrong so i switched them.. again wrong..
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 Mentor Blog Entries: 1 Switching q1 and q2 won't change anything. Show your final expression for the work done and the numbers you plugged in. Is it positive or negative?