The figure shows two conductors of equal radius r located at a centre-to-centre distance of 2H. The charge on each conductor is Q C/m and of opposite polarity. On a unit, a positive charge is located at F at a distance of x from the centre of the left conductor. The total force exerted is given by:

• A. \({E_f} = \frac{Q}{{2\pi {\varepsilon _0}}}\left( {\frac{1}{x} - \frac{1}{{2H + x}}} \right)\)
• B. \({E_f} = \frac{Q}{{2\pi {\varepsilon _0}}}\left( {\frac{1}{x} - \frac{1}{{2H - x}}} \right)\)
• C. \({E_f} = \frac{Q}{{2\pi {\varepsilon _0}}}\left( {\frac{1}{x} + \frac{1}{{2H + x}}} \right)\)
• D. \({E_f} = \frac{Q}{{2\pi {\varepsilon _0}}}\left( {\frac{1}{x} + \frac{1}{{2H - x}}} \right)\)