Wind blowing across suspended power lines may

cause the power lines to vibrate at their natural

frequency. This often produces audible sound

waves. This phenomenon, often called an

Aeolian harp, is an example of

(1) diffraction (3) refraction

(2) the Doppler effect (4) resonance

(4) Resonance

Explanation:

Resonance is a phenomenon in which an external force or a vibrating system forces another system around it to vibrate with greater amplitude at a specified frequency of operation.

Some Examples of Resonance

Musical Instruments

The best examples of resonance can be observed in various musical instruments around us. Whenever any person hits, strikes, strums, drums or tweaks any musical instrument, the instrument is set into oscillation or vibration at the natural frequency of vibration of the instrument. A unique standing wave pattern defines each frequency of vibration as a specific instrument. These natural frequencies of a musical instrument are known as the harmonics of the specified instrument. If a second interconnected object or instrument vibrates or oscillates at that specified frequency then the first object can be forced to vibrate at a frequency higher than its natural harmonic frequency and as such, resonance occurs.

Aoelian Vibration (Harp)

Wind blowing across suspended power lines may cause the power lines to vibrate at their natural frequency. This often produces audible sound waves showing that resonance has occurred due to the frequency of vibration of the wire coninciding with that of the wind.

prndulum needs thread, weight clock to time swings