Calculating voltage from multiple point charges

AI Thread Summary
To calculate the electric potential from multiple point charges, the formula used is v = k(q1/r1 + q2/r2 + q3/r3). In this case, three point charges are positioned at different heights, with the goal of finding the potential at a height of 8 km. The user correctly converted distances from kilometers to meters and summed the contributions from each charge, arriving at a potential of 7.5E7 volts. The negative charge's effect was appropriately subtracted from the total potential. The calculations and approach taken are validated as correct.
Eric_meyers
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Homework Statement


A point charge 10 km in the air with a charge of 40 coulombs
A point charge 5 km in the air with a charge of -40 coulombs
A point chare 2 km in the air with a charge of 10 coulombs
-Find the electric potential due to these charges at a point which at a height of 8 km and on the vertical line passing through the charges.


Homework Equations


kq1/r1 + kq2/r2


The Attempt at a Solution



So I summed them up

v = k (40C/2000m - 40C/3000m + 10C/6000m) = 7.5E7

My question is, is do I need to convert km to m and was I correct in subtracting the negative 40 coulomb charge from the rest of the positive charges?
 
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Yes and yes. Looks good to me.
 

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