Weakly Damped Harmonic Oscillator: Phase Difference

[Amith2006]

Sir,
A weakly damped harmonic oscillator is executing resonant oscillations. What is the phase difference between the oscillator and the external periodic force?

 

[Curious3141]

See : http://en.wikipedia.org/wiki/Driven_harmonic_motion#Simple_harmonic_oscillator

And unless you want to keep getting raw links to online encyclopedia references, show some work.