physics
posted by Nicole on .
There's a problem my professor assigned, but I'm not sure which equation/process I should use to solve it. Please help.
Two particles having charges of 0.420nC and 15.1nC are separated by a distance of 1.50m. At what point along the line (in m from the particle with .420nC charge) connecting the two charges is the net electric field due to the two charges equal to zero? Also, Where would the net electric field be zero if one of the charges were negative? (answer as a distance from the charge initially equal 0.420nC)

It is rather simple. Draw the diagram,
a) let x be the distance from one charge, 1.5x the distance from the other charge. Now, figure E
E=kq/r^2
Now notice that E on each charge is away from the charge. So they are oppositely directed.
then kq1/(r1^2)^2= kq2/(r2)^2
solve for x.
Now on the second part, the x will be outside the line joining them. Do it the same way.