Explain the difference between electrostatic force and gravitational force. 

Ans: (a) Gravitational force ia always attractive. Electrostatic force can be attractive or repulsive, depending on the nature of the charges, 

(b) The gravitational constant G (s independent of the nature of the medium. But the electrical constant depends on the nature of the medium (i.e relative permittivity). 

(c) The electrostatic force is always large compared to the gravitational force