MCQs on Analog Electronics

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01․ The following are the necessary requirements of an oscillator
Amplitude stability
Frequency stability
Power stability
Both A and B

The amplitude and frequency stabilities are the primary requirements for the oscillator which determines the ability to maintain constant amplitude, sustained oscillation and desired frequency of the output waveform.

02․ The Barkhausen criterion for an oscillator
Loop gain should be unity
Loop gain should be less than unity
The phase of a feedback signal with respect to input should be 0° or 360°
Both A and C

Amplitude of oscillations is decided by unity loop gain and frequency of oscillations is controlled by phase angle. To get sustained oscillation both conditions have to be met. .

03․ LC oscillators are used for produce a waveform with frequency ranging from
1MHz to 500 MHz
100 KHz to 500 MHz
1 KHz to 1 MHz
1MHz to 100 GHz

LC oscillators are used to produce the output at frequency ranging from 1 MHz to 500MHz that’s why these are also called as RF (radio frequency) oscillators.

04․ Which of the following oscillators are used for low frequency (LF) applications
LC oscillators
RC oscillators
Both LC and RC Oscillators

RC oscillators are used for LF applications because an LC oscillator is difficult to be realized at low frequencies as the size of the inductor required is very large, expensive and bulky.

05․ The expression for frequency of oscillations of a RC phase shift oscillator is
f = 1 / (2π√RC)
f = 1 / (2π√R(C1 + C2))
f = 1 / (2π RC√6)
none of the above

The frequency oscillations of RC phase shift oscillator is as it contains three RC sections.

06․ A diode (P-N junction) has two terminals. The P-terminal is known as
Either anode or cathode
None of these

A diode is a semiconductor device which is formed by combining the P-type material and N-type material to diffuse together. P-type material has holes as majority carriers while N-type material has electrons as majority carriers. So, the P-type side is anode and N-type side is cathode.

07․ A working diode must have
High resistance when forward or reverse biased
Low resistance when forward biased, while high resistance when reverse bias
High resistance when forward biased, while low resistance when reverse bias
Low resistance when forward or reverse biased

A working diode means the diode is biased or connected with the DC source. When a diode is forward biased ( +ve terminal to anode and -ve terminal to cathode ), it provides a low resistance path because it helps the majority carrier to crossover the barrier potential and conduct the flow of current. When a diode is reversed biased ( -ve terminal to anode and +ve terminal to cathode ) it provide a high resistance path because the majority carriers are flows away from the junction and no current conduction takes place.

08․ Electrons in p-type material of a semi-conductor are called as
either minority carriers or majority carriers
minority carriers
majority carriers
valance carriers

Electrons in p-type and n-type material of a semi-conductor are called as minority charge carriers and majority charge carriers respectively. Electrons are less in number in the p-type as compared to the holes present in it. So, it is a minority carriers in p-type material.

09․ Silicon and Germanium are ________ elements.

Silicon and Germanium belong to group IVa of the periodic table consisting of four electrons in their valance shell, also called as tetravalant elements. Group IVa elements are Carbon (C) (6) Silicon (Si) (14) (2 8 4) Germanium (Ge) (32) (2 8 18 4) Tin (Sn) (50) Lead (Pb) (82)

10․ A diode (p-n junction) when reverse biased act as
On Switch
Zener diode
Off Switch

A diode when reverse biased (positive terminal of the battery is connected to cathode and negative terminal of the battery is connected to anode) does not conduct any considerable electric current and hence acts as an off switch.