Thermal Expansion: Practice Problem & Solution

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Thermal Expansion. Understanding the underlying formula is key to arriving at the correct answer below:

When a metal rod is heated, its atoms gain kinetic energy and vibrate more vigorously. As they vibrate, they tend to move slightly further apart because the increased energy weakens the attractive forces that hold them at a fixed distance. This increased atomic spacing results in the rod expanding in size.

Thus, the expansion of the metal rod occurs because the distance among its atoms increases with temperature. This phenomenon is the essence of thermal expansion.