Question

Question 5. Suppose we have 3 point charges fixed in place in a line as below:

P ............Q.................-Q................-2Q. ( assume equidistance between)

What is the total electric potential due to these three charges at point P?

a.

keQ/6r

b.

-2keQ/r

c.

�keQ/3r

d.

0O

e.

-2keQ/3r

Answer 1

Electric potential is V = k[(Q/r)+(-Q/2r)-(2Q/3r)]

V = (k*Q/r)(-1/6) = -k*Q/6r

so option a is correct

Answer 2

Electric Potential is given as

V = k Q/r

Q = charge   , r = distance from charge

Potential by charge Q at distance ''r'' from point P:

V₁ = k Q /r

Potential by charge -Q at distance ''2r'' from point P:

V₂ = -k Q /2r

Potential by charge -2Q at distance ''3r'' from point P:

V₃ = -k 2Q /3r

Total Electric Potential :

V_total = V1 + V2 + V3\

V_total = (k Q /r )+ (-k Q /2r) + ( -k 2Q /3r)

V_total = -kQ/6r