MHT CET202611 April 2026Morning ShiftPhysicsWaves and SoundActual
What is the effect of humidity on sound waves when humidity increases?
Options
- ASpeed of sound waves is more.
- BSpeed of sound waves is less.
- CSpeed of sound waves remains same.
- DSpeed of sound waves becomes zero.
Correct answer
A. Speed of sound waves is more.
Step-by-step solution
The speed of sound in a gas is given by v = R T M , where M is the molar mass of the gas. Dry air consists mainly of nitrogen ( N₂ , molar mass 28 g/mol) and oxygen ( O₂ , molar mass 32 g/mol), giving an average molar mass of approximately 28.97 g/mol. Water vapor ( H₂O ) has a molar mass of 18 g/mol. When humidity increases, water vapor displaces heavier nitrogen and oxygen molecules, which decreases the average molar mass M of the air. Since the speed of sound is inversely proportional to the square root of the m