What is the force between two small charged spheres having charges of 2 × 10−7 C and 3 × 10−7 C placed 30 cm apart in air?

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Ques: What is the force between two small charged spheres having charges of 2 × 10−7 C and 3 × 10−7 C placed 30 cm apart in air?

Ans: Repulsive force of magnitude 6 × 10−3 N 

 Charge on the first sphere, q1 = 2 × 10−7 C 

 Charge on the second sphere, q2 = 3 × 10−7 C 

 Distance between the spheres, r = 30 cm = 0.3 m

Electrostatic force between the spheres is given by the relation 


 where, 𝜀0 = Permittivity of free space and 1/ 4𝜋𝜀 = 9 × 10^9 Nm² C −2 

Therefore, force 


 Hence, force between the two small charged spheres is 6 × 10−3 N. 

The charges are of same nature. Hence, force between them will be repulsive.

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