Consider 2 charges located in the x-y plane; q1 of magnitude 5 mC (millicoulombs) is located at the origin, and q2 of unknown magnitude is located at (x,y) = (0.1, 0) (in metres). The electric field E at position (0.03, 0.05) is found to be entirely in the +y direction (i.e. the x-component is zero). Determine the sign of charge q1 and the magnitude and sign of charge q2.
|q| = 5mC (microCoulombs)
F= qE ; q= charge, E= electric Field
E(r) = ƩEi(r)
The Attempt at a Solution
E1(for one charge)= 1/(4*pi*ε°)*q1/r2
= 1/(4*pi*ε°)* (0.000005 C)/0.0015m
Then I went and did,
rearrange for q2 and,
q2= -29.9997 C. (This seems way to high to be correct)
So q1 is positive to make E in the + y direction.