Resonance (Edexcel A Level Physics)

The photograph shows a ‘singing bowl’.  

When the handles are rubbed with both hands the bowl ‘sings’, producing a loud note with a frequency of 720 Hz.

A vibration generator is attached to the bowl and connected to a signal generator. The signal generator is adjusted to produce frequencies from 600 Hz to 800 Hz.

At all frequencies in this range the bowl produces a sound at the applied frequency. The sound is quiet for all frequencies except 720 Hz, when it is much louder.

Explain these observations. 

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