Question Detail
Question
An electron (charge $\approx -1.6 \times 10^{-19} \text{ C}$) and a proton (charge $\approx 1.6 \times 10^{-19} \text{ C}$) are separated by a distance of $5.3 \times 10^{-11} \text{ m}$ in a hydrogen atom. What is the electrostatic potential energy of the system?
Correct Answer
Option A is the correct answer.
Detailed Explanation
Using $U = \frac{k \cdot q_1 \cdot q_2}{r}$, we get $U = \frac{(9 \times 10^9) \cdot (1.6 \times 10^{-19}) \cdot (-1.6 \times 10^{-19})}{5.3 \times 10^{-11}}$. The result is approximately $-4.35 \times 10^{-18} \text{ J}$.
Hint
Since the charges have opposite signs, the potential energy must be negative, indicating an attractive force.