Match the List-I with List-II.
A. AC generator   I. Presence of both L and C
B. Transformer   II. Electromagnetic Induction
C. Resonance phenomenon to occur   III. Quality factor
D. Sharpness of resonance   IV. Mutual Inductance

Let us match each item in List-I with the appropriate item in List-II:

A. AC generator - An AC generator works on the principle of Electromagnetic Induction (II). When a coil rotates in a magnetic field, the changing magnetic flux induces an EMF.

B. Transformer - A transformer works on the principle of Mutual Inductance (IV). The changing current in the primary coil induces an EMF in the secondary coil through mutual induction.

C. Resonance phenomenon to occur - Resonance in an AC circuit occurs when both an inductor (L) and capacitor (C) are present, i.e., Presence of both L and C (I). At resonance, $$X_L = X_C$$.

D. Sharpness of resonance - The sharpness of resonance is measured by the Quality factor (III), defined as $$Q = \frac{\omega_0 L}{R} = \frac{1}{R}\sqrt{\frac{L}{C}}$$.

Therefore, the correct matching is: A-II, B-IV, C-I, D-III.