Question

A transistor-oscillator using a resonant circuit with an inductor L ( of negligible resistance ) and a capacitor C in series produce oscillations of frequency f. If L is doubled and C is changed to 4C, the frequency will be

• A. f/4
• B. $F_2=\frac{F_1}{2\sqrt{2}}$
• C. $f/2\sqrt{2}$
• D. f/2

Answer 1

The correct option is B $F_2=\frac{F_1}{2\sqrt{2}}$

A transitor-oscillator using a resonant circuit with a inductor L

(of negligible resistance)

and a capacitor c in series produce oscillations of frequency $=f$'

If L is doubled and C is charged to $4C$ then the frequency.

The formula of $Q-factor$ of transitor oscillator

$f=\frac{1}{2\pi }\sqrt{\frac{1}{LC}}\frac{f_1}{f_2}=\sqrt{\frac{L_2{C}_2}{L_1{C}_1}}=\sqrt{\frac{4C\times 2L}{L\times C}}=\sqrt{8}=\sqrt{4\times 2}=2\sqrt{2}{f}_2=\frac{f_1}{2\sqrt{2}}$