<Dl> <Dd> I (ω) ≡ χ 2 ∝ 1 (ω − Ω) 2 + (Γ 2) 2 . (\ displaystyle I (\ omega) \ equiv \ chi ^ (2) \ propto (\ frac (1) ((\ omega - \ Omega) ^ (2) + \ left ((\ frac (\ Gamma) (2)) \ right) ^ (2))).) </Dd> </Dl> <Dd> I (ω) ≡ χ 2 ∝ 1 (ω − Ω) 2 + (Γ 2) 2 . (\ displaystyle I (\ omega) \ equiv \ chi ^ (2) \ propto (\ frac (1) ((\ omega - \ Omega) ^ (2) + \ left ((\ frac (\ Gamma) (2)) \ right) ^ (2))).) </Dd> <P> Where the susceptibility χ (ω) (\ displaystyle \ chi (\ omega)) links the amplitude of the oscillator to the driving force in frequency space: </P> <P> x (ω) = χ (ω) F (ω) (\ displaystyle x (\ omega) = \ chi (\ omega) F (\ omega)) </P>

What are the conditions necessary for resonance to occur