A +25µC point charge is placed 6.0cm from an identical +25µC point charge. How much work would be required by an external force to move a +0.18µC test charge from a point midway between them to a point 1.0cm closer to either charge?

Explanation:

Required work done = charge moved x potential difference at two points

Potential at mid point

= 2 x k q / r

= 2 x 9 x 10⁹ x 25 x 10⁻⁶ / 3 x 10⁻²

= 150 x 10⁵ V

Potential at the second point

=  9 x 10⁹ x 25 x 10⁻⁶ / 4 x 10⁻²  + 9 x 10⁹ x 25 x 10⁻⁶ / 2 x 10⁻²

= 56.25 x 10⁵ + 112.5 x 10⁵

= 168.75 x 10⁵ V

Potential difference

= (168.75 - 150 ) x 10⁵ V

= 18.75 x 10⁵

Work done

= .18 x 10⁻⁶ x 18.75 x 10⁵ J

= 3.375 x 10⁻¹ J

= .3375 J

are there answer choices to this question? this seems like a question where you have options to choose from.

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement