A charge Q is kept at a distance L from another charge Q. It is now moved to a distance of 2L. What is the potential difference between two positions?

Options

A. `-(Q)/(8piepsilon_(0)L)`
B. `+(Q)/(8piepsilon_(0)L)`
C. `(2Q)/(4piepsilon_(0)L)`
D. `-(2Q)/(4piepsilon_(0)L)`

Answer

A

Explanation

`U_(i)=(1)/(4piepsilon_(0))(Q^(2))/(L),U_(f)=(1)/(4piepsilon_(0))(Q^(2))/(2L)`
`W_("cons")=-DeltaU`, (`W_("cons")` = work done by conservative force)
`W=-(U_(f)-U_(i))=(-Q)/(8piepsilon_(0)L)`