Transistors

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:

• Power amplifier: Used to amplify the power of a signal, not oscillate it.
• Voltage amplifier: Used to amplify the voltage of a signal, again, not for oscillation.
• Full-wave rectifier and half-wave rectifier: Used for converting AC to DC, not for oscillations.

Correct Answer:

Correct Answer: (A) Oscillator

In a Common Base (CB) mode of a transistor, the relationship between the emitter current ( ), base current ( ), and collector current ( ) is given by the following equations:

The current gain ( ) of the transistor is related to the collector current and the base current by the equation: We are given that the current gain and the emitter current . Since , we can substitute into this equation: Substituting the given values: Solving for : Therefore, the base current is approximately 0.4 mA.

Correct Answer:

Correct Answer: (D) 0.4 mA