Question

In the case of sustained forced oscillations the amplitude of oscillations,

• A. Decreases linearly
• B. Decreases sinusoidally
• C. Decreases exponentially
• D. Always remains constant

Answer 1

The correct option is D Always remains constant

Forced oscillations occurs when system interacts with external disturbances (force) which are periodic in nature.
For a sustained forced oscillation, frequency of oscillation will be equal to the frequency of external force at the steady state.

$\Rightarrow$Considering the fact that the external force is sufficient enough to generate the power required for sustaining the oscillation. Hence amplitude of oscillation will always remain constant.
Here work done by the force will impart energy required to maintain the amplitude.