# [Physics] Forced Oscillations & Resonance

oscillatorsresonance

I need a very much physical explanation for the phenomenon of Resonance associated with forced oscillations (damped). I have gone through HRW and Concepts of Physics by H C Verma, but that wasn't of much use for me.

I got some mathematical idea of the thing, but still I'm not confident.

Resonance is when you push a kid on a swing.

If you do it right, you make him swing higher (You push him in the same direction as he is moving). If you do it wrong, you stop his swinging (e.g. pushing, when he is on the way backwards).

When you "add to" or "build up" the amplitude of the oscillations, this is resonance.

You need to push with the same frequency as he is swinging. (If he is swinging back-and-forth in 3 seconds, then you must push forward exactly once every 3 seconds). Also you must be in phase. (Even when your push-frequency is equal to his swing-frequency, you should not push when he is moving backwards.)

I need a very much physical explanation for the phenomenon of Resonance associated with forced oscillations (damped)

A damped oscillation only changes amplitude with time. Not frequency. Resonance is not different in this case.

If you want a steady oscillation with constant amplitude, then of course you need to force an oscillation on the system and reach resonance to cancel out the damping.