Question

An electron is brought towards another electron. The magnitude of the electric potential energy of the system:
1. decreases
2. increases
3. does not change
4. becomes zero

Answer 1

Correct Answer - Option 2 : increases

CONCEPT:

• Electric potential energy: The electric potential energy of a system of charges is defined as the amount of work done in bringing the various charges from infinite separation to their present position to form the required system.

For the system of two charges the electric potential energy is given as:

\(\Rightarrow U=\frac{kQq}{r}\)

Where U electric potential energy, k = 9×10⁹ N-m²/C², Q and q = two charges and r = distance between the two charges

EXPLANATION:

• For the system of two charges the electric potential energy is given as,

\(\Rightarrow U=\frac{kQq}{r}\)

Since k, Q and q are constant,

\(\Rightarrow U\propto\frac{1}{r}\)     -----(1)

• From the above equation, it is clear that the potential energy will increase when the distance between the two charges decreases.
• So when an electron is brought towards another electron the distance between them gets decreases. Hence the potential energy will increase. Therefore, option 2 is correct.