Two point charges, $q_a$ and $q_b$, are separated by a distance $r$. What is the magnitude of the electric force on charge $q_a$ due to $q_b$ according to Coulomb's Law?

• A. $\frac{k\mid q_a\mid \mid q_b\mid }{r^2}$
• B. $\frac{k\mid q_a\mid \mid q_b\mid }{r}$
• C. $\frac{k\mid q_a+q_b\mid }{r}$
• D. $\frac{k\mid q_a\mid }{r}$

Answer: (A)

Verified step by step guidance

1. Identify the two point charges involved: \( q_a \) and \( q_b \), and the distance \( r \) separating them.
2. Recall Coulomb's Law, which states that the magnitude of the electric force \( F \) between two point charges is proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.
3. Write down the formula for Coulomb's Law: \[ F = k \frac{ |q_a| \cdot |q_b| }{ r^2 } \] where \( k \) is Coulomb's constant.
4. Understand that the absolute values of the charges are used because the formula gives the magnitude of the force, which is always positive regardless of the sign of the charges.
5. Use this formula to calculate the magnitude of the force on charge \( q_a \) due to charge \( q_b \) by substituting the known values of \( q_a \), \( q_b \), \( r \), and \( k \).