Question

Two charge spears are 20 cm apart and extract an attractive force of 8x10^-9 N on each other. Which will be the force of attraction when the Spheres are moved to 10 cm apart ?

Answer 1

Answer:

3.2 × 10⁻⁸ N.

Explanation:

By Coulomb's Law, the magnitude of the electromagnetic force between two point charges is inversely proportional to the square of their separation, $r$. In other words,

$\displaystyle \frac{F_1}{F_2} = {\left(\frac{r_2}{r_1}\right)}^{2}$.

• Initial electromagnetic force $F_1 = 8\times 10^{-9}\;\text{N}$;
• Initial Separation $r_1 = 20\;\text{cm}$;
• Final Separation $r_2 = 10\;\text{cm}$.

Final electromagnetic force:

$\displaystyle F_2 = F_1 \cdot \left(\frac{r_2}{r_1}\right)^{2} = 8\times 10^{-9}\times \left( \frac{20}{10}\right)^{2} = 3.2\times 10^{-8}\;\text{N}$.