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Analog Electronics

Study 46 Electrical Engineering MCQs with correct answers and explanations.

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21Electrical EngineeringMedium

Generally, the gain of a transistor amplifier falls at high frequencies due to the________?

ASkin effect

BCoupling capacitor at the output

CCoupling capacitor at the input

DInternal Capacitance of the device

Correct answer

D. Internal Capacitance of the device

Explanation

The correct answer is Internal Capacitance of the device.

22Electrical EngineeringMedium

The effective channel length of a MOSFET in a saturation decreases with increase in________?

ASource voltage

BGate voltage

CDrain voltage

DBody voltage

Correct answer

C. Drain voltage

Explanation

The correct answer is Drain voltage.

23Electrical EngineeringMedium

Three identical amplifiers with each one having a voltage gain of 50,input resistance of 1KΩ & output resistance of 250,are cascaded.The open circuit voltage gain of combined amplifier is________?

A49dB

B98dB

C102dB

D51dB

Correct answer

B. 98dB

Explanation

The correct answer is 98dB.

24Electrical EngineeringMedium

When a transistor is connected in common emitter mode, it with have________?

Alow input resistance as well as output resistance

Bhigh input resistance and low output resistance

Cnegligible input resistance and high output resistance

Dmedium input resistance and high output resistance

Correct answer

D. medium input resistance and high output resistance

Explanation

The correct answer is medium input resistance and high output resistance.

25Electrical EngineeringMedium

The current gain of a bipolar transistor drops at high frequencies because of________?

AThe early effect

BHigh current effects in the base

CParasitic inductive elements

DTransistor capacitances

Correct answer

D. Transistor capacitances

Explanation

The correct answer is Transistor capacitances.

26Electrical EngineeringMedium

An n- channel JFET has IDSS=2mA,and Vp=-4v.Its transconductance gm=in mA/V)for an applied gate to source voltage VGS=-2v is________?

A0.75

B0.25

D0.5

Correct answer

D. 0.5

Explanation

The correct answer is 0.5.

27Electrical EngineeringMedium

An npn BJT has gm=38mA/v, cµ =10¯14 F, cπ =10¯13F and DC current gain β0=90.For this transistor fT & fβ are________?

AfT =1.33 x 1012 Hz & fβ = 1.47 x 1010 Hz

BfT =1.64 x 108 Hz & fβ = 1.47 x 1010 Hz.

CfT =1.47 x 1010 Hz & fβ = 1.33 x 1012 Hz

DfT =1.47 x 1010 Hz & fβ = 1.64 x 108 Hz

Correct answer

D. fT =1.47 x 1010 Hz & fβ = 1.64 x 108 Hz

Explanation

The correct answer is fT =1.47 x 1010 Hz & fβ = 1.64 x 108 Hz.

28Electrical EngineeringMedium

Which of the following is not associated with a p-n junction?

Ajunction capacitance

Bdepletion capacitance

Cchannel length modulation

Dcharge storage capacitance

Correct answer

C. channel length modulation

Explanation

The correct answer is channel length modulation.

29Electrical EngineeringMedium

To prevent a DC return between source and load, it is necessary to use________?

Acapacitor between source and load

Bresistor between source and load

Cinductor between source and load

Deither A. or B.

Correct answer

A. capacitor between source and load

Explanation

The correct answer is capacitor between source and load.

30Electrical EngineeringMedium

In a common emitter, unbypassed resister provides________?

Avoltage shunt feedback

Bnegative voltage feedback

Ccurrent series feedback

Dpositive current feedback

Correct answer

B. negative voltage feedback

Explanation

The correct answer is negative voltage feedback.

When a transistor is connected in common emitter mode, it with have________?

Alow input resistance as well as output resistance

Bhigh input resistance and low output resistance

Cnegligible input resistance and high output resistance

Dmedium input resistance and high output resistance

Correct answer

D. medium input resistance and high output resistance

Explanation

The correct answer is medium input resistance and high output resistance.

An npn BJT has gm=38mA/v, cµ =10¯14 F, cπ =10¯13F and DC current gain β0=90.For this transistor fT & fβ are________?

AfT =1.33 x 1012 Hz & fβ = 1.47 x 1010 Hz

BfT =1.64 x 108 Hz & fβ = 1.47 x 1010 Hz.

CfT =1.47 x 1010 Hz & fβ = 1.33 x 1012 Hz

DfT =1.47 x 1010 Hz & fβ = 1.64 x 108 Hz

Correct answer

D. fT =1.47 x 1010 Hz & fβ = 1.64 x 108 Hz

Explanation

The correct answer is fT =1.47 x 1010 Hz & fβ = 1.64 x 108 Hz.