Three point charges, which initially are infinitely far apart, are placed at the corners of an equilateral triangle with sides d. Two of the point charges are identical and have charge q.If zero net work is required to place the three charges at the corners of the triangles, what must the value of the third charge be?

Options

A. `-q//4`
B. `-q//2`
C. `q//2`
D. `q//4`

Answer

B

Explanation

U=0
`:. k((qxxq)/a+(qxxQ)/a+(qxxQ)/a)=0`
or `Q=-q/2`