Question

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?

Answer 1

F= k q1 ×q2 / r²

F = 6 x 10^-14 × 9× 10^9 / 30 × 10^-2

F=54 × 10^-14 × 10^11 / 30

F = 54 ×10^-3 / 30

F= 1.8× 10^-3 N

Answer 2

Hey there !!!!!

Force exerted by two charges q₁and q₂ separated by a distance r is

F= q₁q₂/4πεr²

Here,

q₁=2*10⁻⁷C   q₂=3*10⁻7C   r=30cm =30*10⁻²m

1/4πε is a const value =9*10⁹


Force exerted by q₁ q₂ = 2*3*(10⁻⁷)²*9*10⁹/3*10⁻¹
                      =54*10⁻¹⁴*10⁹/3*10⁻¹
                      =18*10⁻⁵*10
                       =18*10⁻⁴N