The four particles are fixed in place and have charges q1 = q2 = 4e, q3 = 2e, and q4 = -11e. Distance d = 3.98 μm. What is the magnitude of the net electric field at point P due to the particles?
http://edugen.wileyplus.com/edugen/courses/crs4957/art/qb/qu/c22/q10.jpg
I know the x=0 but for y do you have to find the effect of q4 on q3?

Question

The four particles are fixed in place and have charges q1 = q2 = 4e, q3 = 2e, and q4 = -11e. Distance d = 3.98 μm. What is the magnitude of the net electric field at point P due to the particles?
http://edugen.wileyplus.com/edugen/courses/crs4957/art/qb/qu/c22/q10.jpg
I know the x=0 but for y do you have to find the effect of q4 on q3?

noelgreco · Answer

Do you see why you needn't consider the fields due to q1 and q2?

anonymous · Answer

Yes, because they cancel out.