What is resonance?

• A. The amplification of sound when an object vibrates at its natural frequency.
• B. The absorption of sound by a material.
• C. The reflection of sound waves.
• D. The emission of light by a vibrating object.

Answer: (A)

Resonance is when a system is driven at or near its natural frequency, causing large amplitude vibrations. When the driving frequency matches the object's natural frequency, energy is transferred efficiently and each push adds in phase with the motion, building up the vibration and making the sound louder. In acoustics and music, this explains why certain shapes and instruments amplify specific tones—their resonant frequencies produce a strong, reinforced response. A familiar example is singing a note that matches a wine glass’s natural pitch, causing the glass to vibrate loudly. This amplification differs from absorption, which dampens vibrations; reflection, which simply bounces waves away; and emission of light, which is a different physical process.