A series combination of resistor of resistance 100 $$\Omega$$, inductor of inductance 1 H and capacitor of capacitance 6.25 $$\mu$$F is connected to an ac source. The quality factor of the circuit will be _____.

We have resistance $$R = 100$$ $$\Omega$$, inductance $$L = 1$$ H, and capacitance $$C = 6.25$$ $$\mu$$F = $$6.25 \times 10^{-6}$$ F.

The quality factor of an RLC series circuit is given by:

$$Q = \frac{1}{R}\sqrt{\frac{L}{C}}$$

Substituting the values:

$$Q = \frac{1}{100}\sqrt{\frac{1}{6.25 \times 10^{-6}}}$$

$$Q = \frac{1}{100}\sqrt{\frac{10^6}{6.25}}$$

$$Q = \frac{1}{100}\sqrt{1.6 \times 10^5}$$

$$Q = \frac{1}{100} \times 400 = 4$$

So, the answer is $$4$$.