Consider a coin of Example 1.20. It is electrically neutral and contains equal amounts of positive and negative charge of magnitude 34.8 kC. Suppose that these equal charges were concentrated in two point charges separated by (i) 1 cm , (ii) 100 m ( ∼length of a long building), and (iii) 106 m (radius of the earth). Find the force on each such point charge in each of the three cases. What do you conclude from these results?

Let, q be the magnitude of the charge.


Also let,


r1 be the distance in first case.


r2 be the distance in second case.


r3 be the distance in third case.


According to the question,


q = ± 34.8 KC and i.e. = ± 3.48 × 104 C


r1 = 1 cm = 10‒2 m


r2 = 100 m


r3 = 106 m


Let’s assume, F1, F2 and F3 are forces in first, second and third case respectively, then by using







×






So we have,





It is not easy to disturb the electrical neutrality.


When the charges are separated as point charges the charges exert a huge force.


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