Question

The figure below shows three charged spheres arranged along the y axis. (Assume q_1 = 2.40 muC and q_2 = 4.3 mu C. Express your answer in vector form.) (b) What is the electric field at x = 0, y = 3.50 m? E vector = times N/C

Answer 1

Given that
q1 = 2.40 uC
q2 = 4.35 uC
q3 = - 4.80 uC

(a)
Ey = k*q1/r1^2 + k*q2/r2^2 + k*q3/r3^2

Ey = (8.9*10^9*10^-6) * [ 2.40/(3.50 - 0.75)^2 - 4.80/2.6^2 + 4.35/(2.6 + 0.22)^2 ]

Ey = 1373 J^ N/C

(b)
At x = 3.50 cm
r1 = sqrt(0.75^2 + 3.50^2)
r1 = 3.579 m

r2 = sqrt(0.22^2 + 3.50^2)
r2 = 3.506 m

Ex = k*q1/r1^2 * 3.50/3.579 + k*q2/r2^2 * 3.50/3.506 - k*q3/r3^2

Ex = (8.9*10^3) * [ 2.40/3.579^2 * 3.50/3.579 + 4.35/3.506^2 * 3.50/3.506 - 4.80/3.50^2 ]

Ex = 1287.6 i^ N/C

Ey = - k*q1/r1^2 * 0.75/2.706 + k*q2/r2^2 * 0.22/2.609

Ey = (8.9*10^3) * [ - 2.40/3.579^2 * 0.75/3.579 + 4.35/3.506^2 * 0.22/3.506]

Ey = - 547 j^ N/C

E = 1287.6 i^ - 547 j^ N/C