Aphysicist found that a force of 0.68 n was measured between two charged spheres. the distance between the spheres was 1.0 m. calculate the force between the two spheres when the distance was decreased to 0.50 m.

The force between two system is inversely proportional to the square the distance between them. The indirect proportion between these items may be expressed as,
                                           F = k / d²
where k is the constant proportionality. Substituting the known values, 
                                     0.68 N = k / (1 m)²     ; k = 0.68
For the second case, 
                                     F = 0.68 / (0.5 m)² = 2.72 N
Thus, the answer is 2.72 N.

An atom that has fewer electrons that protons is called a positive ion.