What is a practical way to demonstrate resonance using a glass of water?

• A. Making music with a hang drum
• B. Rubbing the rim of the glass to produce sound
• C. Pouring water rapidly into the glass
• D. Placing the glass in direct sunlight

Answer: (B)

Rubbing the rim of a glass to produce sound is a practical and effective way to demonstrate resonance. When the rim is rubbed, the friction generates vibrations that travel through the glass. These vibrations can excite the natural resonant frequencies of the glass, amplifying certain pitches and creating a musical tone. This phenomenon occurs because the physical properties of the glass and the shape of the vessel allow it to resonate at specific frequencies when energy is applied in the form of friction.

The other options do not effectively demonstrate the concept of resonance. Making music with a hang drum involves different principles of sound production and not the same direct involvement of a resonating medium. Pouring water into the glass does not create a sustained vibration or sound that illustrates resonance; instead, it merely introduces motion without enhancing the resonant properties. Placing the glass in direct sunlight has no direct relation to sound or resonance, as it pertains more to thermal effects rather than acoustic phenomena. Thus, rubbing the rim is a clear and practical demonstration of the principles behind resonance in sound.