Match List - I with List - II.
| List-I | List-II |
| Physical Quantities | Expression |
| (A) Electrostatic Force | (I) \( \frac{1}{4\pi\varepsilon_0}\frac{q}{r} \) |
| (B) Electrostatic Potential | (II) \( \frac{1}{4\pi\varepsilon_0}\frac{q_1 q_2}{r} \) |
| (C) Electrostatic Potential Energy | (III) \( \frac{1}{4\pi\varepsilon_0}\frac{q_1 q_2}{r^2} \) |
| (D) Electrostatic field due to point charge | (IV) \( \frac{1}{4\pi\varepsilon_0}\frac{q}{r^2} \) |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) - (III), (B) - (I), (C) - (II), (D) - (IV)
Two charges in an expression mean an interaction between them (force or potential energy); one charge means a property of the space around a single charge (field or potential). An inverse square of distance goes with the vector quantities (force, field); a plain \( 1/r \) goes with the scalar energy quantities.
(A) Electrostatic Force — this matches (III) \( \frac{1}{4\pi\varepsilon_0}\frac{q_1 q_2}{r^2} \). This is Coulomb's law for the force between two charges.
(B) Electrostatic Potential — this matches (I) \( \frac{1}{4\pi\varepsilon_0}\frac{q}{r} \). The potential of a single point charge falls as \( 1/r \).
(C) Electrostatic Potential Energy — this matches (II) \( \frac{1}{4\pi\varepsilon_0}\frac{q_1 q_2}{r} \). The potential energy of two charges is \( q_2 \) times the potential of \( q_1 \) at the position of \( q_2 \), so it carries both charges and \( 1/r \).
(D) Electrostatic field due to point charge — this matches (IV) \( \frac{1}{4\pi\varepsilon_0}\frac{q}{r^2} \). The field is the force per unit test charge, so dividing Coulomb's force by \( q_2 \) leaves \( q/r^{2} \).