Two point charges are separated by a distance of 100 mm100\text{ mm}100 mm. The force of attraction between them is 720 μN720\ \mu\text{N}720 μN. The distance between the point charges is increased by 300 mm300\text{ mm}300 mm.
What is the new force of attraction?
45 μN45\ \mu\text{N}45 μN
80 μN80\ \mu\text{N}80 μN
180 μN180\ \mu\text{N}180 μN
240 μN240\ \mu\text{N}240 μN
