comparison of electrostatic force and gravitational force

“comparison of electrostatic force and gravitational force”:

*similarities :

1) Both the forces obey the inverse square law. 

2) These two forces operates in vacuum. 

3) These are conservative forces. 

4) Both having central forces. 

* Dissimilarity: 

1) Electrostatic force can be either attractive or repulsive but gravitational force is always attractive in nature. 

2) The presence of dielectric medium effect the electrostatic force but the medium has no effect on gravitational force. 

3) Electrostatic force is more stronger than gravitational force. 

*Note: “Composition of proton and neutron”

1) up quarks = +2/3 e

2) Down quarks = - 1/3 e

 Proton = 2 up quarks + 1 down quarks 

             = 2(+2/3 e) +1(-1/3 e) 

             = +4/3 e - 1/3 e

             = +3/3 e

             = +e

Charge on proton , +e = +1.6×10^-19C

Neutron  = 1 up quarks + 2 down quarks 

                 = 1(+2/3 e)  + 2(-1/3 e) 

                 = +2/3 e - 2/3 e

                 = 0

Charge on neutron = 0

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