WBCS.LIVE practice question

A metallic ball has a spherical cavity at its centre. If the ball is heated what happens to the cavity?

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. Its volume decreases
  2. Its volume increases
  3. Its volume remains unchanged
  4. Its volume may increase or decrease depending upon the nature of the metal.

Correct answer and explanation

Correct answer: Its volume increases

Explanation: When a metallic ball with a cavity is heated, the cavity volume increases because expansion occurs uniformly in all directions. 📚 Other Information: ▪️ Thermal expansion applies to solids, liquids, and gases. ▪️ Even the inner cavity expands as if it is filled with the same material. ▪️ Coefficient of expansion defines the rate of increase in volume. ▪️ Commonly used in railway tracks and bridges (expansion joints). ▪️ Expansion may cause cracks if not accounted for. ▪️ Practical applications: bimetallic strips in thermometers. ▪️ Important in metallurgy and construction industries. ▪️ Explains why tight lids can be opened by heating.