Question

Instantaneous power delivered to a damped harmonic oscillator (natural frequency is $\omega_0$) by an external periodic force (driving frequency $\omega$) under steady state conditions is

• A. positive always
• B. negative always
• C. positive and negative with power integrated over a period being zero
• D. positive and negative with power integrated over a period being positive
• E. positive and negative with power integrated over a period being negative

Answer 1

Answer: (A)

As we know in damped harmonic oscillation the amplitude of oscillation dies away with time. Hence for steady state, continuous external periodic force (driving frequency) is required or in other word a continuous supply of positive power is required.