Question

Coulomb's law states that the force between two point charges \(Q_1\) and \(Q_2\) is :
• [A.] Along the line joining them.
• [B.] Directly proportional to the product of charges \(Q_1\) and \(Q_2\).
• [C.] Inversely proportional to the distance \(R\) between them.
• [D.] Inversely proportional to the square of distance \(R\) between them. Choose the correct answer from the options given below :

• A. A, B, C Only
• B. A, B, D Only
• C. B, C Only
• D. B, D Only

Hint:

Coulomb’s law: \[ F=\frac{1}{4\pi\epsilon}\frac{Q_1Q_2}{R^2} \] Electrostatic force follows inverse square law.

Answer 1

The Correct Option is B

Concept: Coulomb’s law gives the electrostatic force between two point charges. The magnitude of force is: \[ F=\frac{1}{4\pi\epsilon}\frac{|Q_1Q_2|}{R^2} \] where:
• \(Q_1,Q_2\) are point charges
• \(R\) is separation distance
• \(\epsilon\) is permittivity

Step 1: Analyze statement A. Electrostatic force acts: \[ \text{Along the line joining the two charges} \] Hence: \[ A \text{ is correct} \]

Step 2: Analyze statement B. From Coulomb's law: \[ F\propto Q_1Q_2 \] Thus force is directly proportional to product of charges. Therefore: \[ B \text{ is correct} \]

Step 3: Analyze statement C. Statement C says: \[ F\propto \frac{1}{R} \] This is incorrect because Coulomb’s law contains: \[ \frac{1}{R^2} \] not: \[ \frac{1}{R} \] Hence: \[ C \text{ is incorrect} \]

Step 4: Analyze statement D. From Coulomb's law: \[ F\propto \frac{1}{R^2} \] Thus statement D is correct. \[ D \text{ is correct} \]

Step 5: Write the final answer. Correct statements are: \[ A,\ B,\ D \] Hence the correct option is: \[ \boxed{(B)\ A,\ B,\ D \text{ Only}} \]