oscillator
power amplifier
A transistor amplifier with a tank circuit and positive feedback will act as an oscillator, not a power amplifier or a voltage amplifier. The tank circuit typically consists of a capacitor and an inductor that form a resonant circuit. When positive feedback is applied to this circuit, it results in sustained oscillations.
In the case of a transistor amplifier, positive feedback helps in producing continuous oscillations, which is the characteristic behavior of an oscillator. Oscillators are used in applications such as signal generators, radio frequency (RF) generation, etc.
However, the other options are incorrect because:
Correct Answer: (A) Oscillator
In the circuit shown, the identical transistors Q1 and Q2 are biased in the active region with \( \beta = 120 \). The Zener diode is in the breakdown region with \( V_Z = 5 \, V \) and \( I_Z = 25 \, mA \). If \( I_L = 12 \, mA \) and \( V_{EB1} = V_{EB2} = 0.7 \, V \), then the values of \( R_1 \) and \( R_2 \) (in \( k\Omega \), rounded off to one decimal place) are _________, respectively.
If the voltage across a bulb rated 220V – 60W drops by 1.5% of its rated value, the percentage drop in the rated value of the power is: