Physics MCQs
Topic Notes: Physics
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
What is the primary effect of negative feedback on an amplifier's performance?
Answer:
Increases bandwidth and decreases noise
Negative feedback involves feeding a portion of the output signal back to the input in phase opposition. This technique is widely used in amplifier design because it stabilizes the gain, reduces non-linear distortion, and minimizes internal noise. Furthermore, it significantly increases the bandwidth of the amplifier, allowing it to operate effectively over a wider range of frequencies, although it does result in a reduction of the overall voltage gain.
2
What is the primary function of an electronic amplifier?
Answer:
To increase the voltage, power or current, of the input signals
An amplifier is an electronic device designed to increase the magnitude of an input signal. It uses an external power source to boost the voltage, current, or power of the signal while ideally maintaining the original waveform shape, allowing weak signals to be processed or transmitted effectively.
3
In which electronic circuit is positive feedback primarily utilized?
Answer:
Oscillators
Positive feedback occurs when a portion of the output signal is fed back to the input in phase with the original signal. This mechanism is essential for oscillators, as it sustains continuous oscillations by compensating for energy losses within the circuit, allowing it to generate a periodic waveform without an external input signal.
4
What is the term for an analog circuit designed to increase the power or amplitude of a signal sufficiently to drive a loudspeaker?
Answer:
amplifier
An amplifier is an electronic device that increases the voltage, current, or power of a signal. In audio systems, an amplifier takes a low-power input signal from a source (like a microphone or media player) and boosts it to a level capable of driving the voice coil of a loudspeaker, converting electrical energy into sound waves without significantly distorting the original waveform.
5
Which of the following characteristics is a defining feature of a non-inverting amplifier circuit?
Answer:
A very high input impedance
Non-inverting amplifier circuits are characterized by extremely high input impedance. This is a critical advantage because it minimizes the loading effect on the signal source, ensuring that the source voltage is effectively transferred to the amplifier. This high impedance makes the circuit ideal for buffering applications where signal integrity must be maintained without drawing significant current from the preceding stage.
6
What are the primary effects of applying negative feedback in an electronic amplifier circuit?
Answer:
increases bandwidth and decreases noise
Negative feedback involves feeding a portion of the output signal back to the input in phase opposition. This process stabilizes the gain, reduces non-linear distortion and noise, and significantly increases the bandwidth of the amplifier, although it results in a reduction of the overall voltage gain.
7
Which of the following electronic components is specifically designed to function as an amplifying device?
Answer:
Transistor
A transistor is a semiconductor device used to amplify or switch electrical signals and power. By controlling a small current or voltage at the base or gate terminal, it can control a much larger current flowing between the other terminals, thus providing signal amplification.
8
When an electronic amplifier processes a signal, which fundamental property of the signal remains unchanged?
Answer:
shape
An ideal amplifier increases the amplitude (size) of an input signal while preserving its original waveform or shape. If the shape were altered, the amplifier would be introducing distortion. Frequency and wavelength are properties that can be manipulated by other circuits, but the primary goal of amplification is to maintain the signal's integrity.