Topic 13 Oscillations

Question 1

If damping is decreased what happens to maximum amplitude, and frequency at which maximum amplitude occurs at? (1)

Answer 1

-Maximum amplitude increases, frequency at which maximum amplitude occurs at increases.

Question 2

When the handles of a ‘singing bowl’ 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. (6)

Answer 2

-720Hz is the natural frequency of the bowl.
-The generator/hand causes forced oscilations.
-When they dont match the natural frequency they are quiet because less energy is transferred.
-Loudness at 720Hz is because of resonance.
-Resonance occurs when driving frequency=natural frequency.
-When resonance occurs there is a maximum transfer of energy so amplitude is maximum.

Question 3

Explain what is meant by resonance. (2)

Answer 3

-The natural frequency=driving frequency.
-Causing there to be a maximum transfer of energy, causing maximum amplitude to increase.

Question 4

Explain how damping results in reduced oscillations. (3)

Answer 4

-Energy was transferred from oscillating system to dampers.
-Energy was dissipated in dampers.
-Hence amplitude of oscillations was kept small.