Question

Two charges repel each other. W ith a force of 0.01 Newton when they are 0.40 M apart calculate the force between them when they are 20 CM apart

Answer 1

F₁ = 0.01 N 

r₁ = 0.40 m 

F₂ = ? 

r₂ = 20 x 10⁻² m 

F₁ = 1/4πε x q₁q₂ /(r₁)²

F₂ = 1/4πε x q₁q₂ /(r₂)²

F₁/F₂ = (r₂)²/ (r₁)² 

0.01 / F₂ = 20 x 20 x 10⁻⁴ / 0.4 x 0.4 

F₂ = 1 x 0.4 x 0.4  x 10⁴ /100 x 20 x 20 

F₂ = 16 x 10⁴ / 10² x 10² x 4 x 10²

F₂ = 4 x 10⁽⁴⁻²⁻²⁻²⁾

F₂ = 4 x 10⁻² = 0.04  N