Question

Amplitude of vibrations remains constant in case of
$\left(i\right)$ free vibrations
$\left(ii\right)$ damped vibrations
$\left(iii\right)$ maintained vibrations
$\left(iv\right)$ forced vibrations

• A. $\left(i\right)$, $\left(iii\right)$ and $\left(iv\right)$
• B. $\left(ii\right)$ and $\left(iii\right)$
• C. $\left(i\right)$, $\left(ii\right)$ and $\left(iii\right)$
• D. $\left(ii\right)$ and $\left(iv\right)$

Answer 1

The correct option is A $\left(i\right)$, $\left(iii\right)$ and $\left(iv\right)$

In free vibrations, amplitude of vibrations remains constant. This is achieved when there is no resistive forces i.e ideally free vibration will occur in vaccum.

In damped vibrations, amplitude of vibrations decreases exponentially with time and expressed as $A=A_0{e}^{-bt}$.

In maintained vibrations, since the energy is supplied to the oscillator at the same rate at which it is dissipated, amplitude of oscillations remains unchanged.

In case of forced oscillations, amplitude of vibrations remains constant as it is understood that force is sufficient enough to provide the energy to maintain the amplitude.
$\therefore \left(i\right),\left(iii\right),\left(iv\right)$ are correct.