Three fixed charges are located along a line. The - 2 C charge is 10cm to the left of the +5 C charge and the -4 C charge at 4 cm to the right of the +5 C charge.

Question

a.what is the force exerted on the -4 C by the +5C charge?
b.what is the force exerted on the -4 C by the -2 C charge?
c.what is the net force exerted on the -4 C charge?

Answer 1

let q1= -2C, q2= +5C, q3= -4C
also r13=10+4=14cm=0.14m
& r23= 4cm = 0.04m

a) Force on q3 due to q2:
F32= k*q3*q2/(r23)^2 towards left

b)Force on q3 due to q1:
F31= k*q3*q1/(r13)^2 towards right

c) Net force on q3 = F32-F31