Two point charges, 3.0 µC and -2.0 µC, are placed 4.4 cm apart on the x axis, su

Question

Two point charges, 3.0 µC and -2.0 µC, are placed 4.4 cm apart on the x axis, such that the -2.0 µC charge is at x = 0 and the 3.0 µC charge is at x = 4.4 cm.

(a) At what point(s) along the x axis is the electric field zero? (If there is no point where E = 0 in a region, enter "0" in that box.)

x < 0 ________cm
0 < x < 4.4 cm ________cm
4.4 cm < x _________ cm

(b) At what point(s) along the x axis is the potential zero? Let V = 0 at r = . (If there is no point where V = 0 in a region, enter "0" in that box.)

Thank you!

Explanation / Answer

A. Suppose at a point P(distance x from origin), total electric field is zero.

Ep = E1 + E2 = 0

E1 = -E2

d = 4.4 cm

kq1/x^2 = kq2/(d-x)^2

[x/(d-x)]^2 = q1/q2

[x/(4.4 - x)]^2 = 2/3

x1 = 1.97 cm to the right side of negative charge.

B. Suppose at a point P(distance x from origin), total electric potential is zero.

Vp = V1 + V2 = 0

V1 = -V2

d = 4.4 cm

kq1/x = kq2/(d-x)

[x/(d-x)] = q1/q2

[x/(4.4 - x)] = 2/3

x1 = 1.76 cm

x2 = -8.8 cm

Comment below if you have any doubt.

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