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

Solution :

Given :

a)      q ₁ = 2 × 10 ^{– 7} C

b)      q ₂ = 3 × 10 ^{– 7} C

c)       r   = 30 cm = 30 X 10 ^{– 3} = 3 X 10 ^{– 2}

d)      ε ₀ = 8.854 × 10 ^{– 12} C ² N ^–1 m^{– 2}

Formula : 

The force between two small charged spheres can be given as

F = [ 1 / ( 4 π ε₀ ) ] [ ( q₁ q₂) / ( r² ) ]

Therefore,

F = [ 1 / ( 4 X 3.14 X 8.854 × 10^–12 ) ] { ( 2 × 10^–7 X 3 × 10^–7) / [ ( 3 X 10^{– 2})² ] }

F = [ 1/(1.11 × 10^–10 ) ] [ ( 6 × 10^–14 ) / ( 9 X 10 ^–4 ) ]

F = [ 9 X 10 ⁹ ) ] [ ( 6 × 10^–10 ) / ( 9 ) ]

F = 60 N

The force between two small charged spheres having charges of 2 × 10^–7C and 3 × 10^–7C placed 30 cm apart in air is 60 newton