Question

When the oscillations produced are of constant amplitude. They are called.

Answer 1

Hint: Oscillation means the process of repeating motion of any quantity about its equilibrium with time. Oscillation can also be defined as a periodic motion of a matter between two extreme positions about its mean position. Any kind of oscillation can not remain constant but when they are constant i.e., amplitude remains the same then they are called undamped oscillation.

Complete answer:
In damped oscillation the amplitude of the vibration or the motion continuously decreases with the time and finally ceases. But undamped oscillations have constant amplitude and they do not change with time, but they go on repeating continuously. They oscillate indefinitely. Undamped oscillations have no power losses. Whereas the damped oscillation has power losses. Generally, every vibration is more or less damped, so to get to undamped vibrations we need to supply energy from the external source to make them damped.
The graph below represents the damped and the undamped vibrations.

In the above graph the damped and undamped oscillations are shown where we can observe that in the damped one the maximum amplitude continuously decreases to zero and in the undamped one the amplitude remains unchanged it continues to remain the same indefinitely.

Note:
The oscillations are mainly the vibrations in which amplitude decreases with time for every kind of oscillation but for an undamped oscillation we need to provide extra energy from the external source to get the amplitude to a constant magnitude. This kind of oscillation is not naturally obtained. Extra effort is required to get to a fixed amplitude.