Question

For point charge -9.6 µC and point charge 5.3 µC located at the same positions as in the previous question (5 m and 4 m, respectively), determine the direction of the net electric field E at the origin. 1µC = 10-6C Your answer should be an integer, do not include the unit.

Answer 1

Given data can be written as

   origin-------- 5.3*10^-6 c, --(-9.6*10^-6C)
   <-------4m---->
   <-----------5m--------------->

we know that the electric field lines for -ve charge is towards the charge and for +ve charge the field lines are away from the charge

here the field at the origin due to -ve charge is towards +ve x direction and due to +ve charge it is towards _ve x-axis

and the magnitude is E = k*q/r^2
due to 5.3*10^-6 c is say
   E1 = (9*10^9*5.3*10^-6)/(4^2) N/C
   E1 = 2981.25 N/C

directed to -ve x-direction

and

due to -9.6*10^-6 c is say

   E2 = (9*10^9*9.6*10^-6)/(5^2) N/C
   E2 = 3456 N/C

directed to +ve x-direction         

net field at the origin is E = E1+E2

   E = -2981.25 + 3456 N/C

   E = 474.75 N/C
the direction is to the right ( towards the +ve X-direction )