Basic Electrical and Electronic Engineering Very Important Questions For External Exams

Question Bank

Define electric current

Define electric resistance

Define electric conductance

Define specific resistance

Differentiate electric power and energy

Define electromotive force

State ohms law

State kirchoff’s law

What is an alternating quantity?

Define cycle

Define time period

Define frequency

Define amplitude

Define RMS value

Define average value

Define the expression for form factor and peak factor

Define power factor

What do you understand by balanced system?

What is an indicating instrument?

Write two essential requirements of indicating instruments

List the three different torques employed in the measuring instruments for the satisfactory operation

Write any four methods by which the deflecting torque can be obtained

Mention the two methods of obtaining controlling torque

What is meant by damping torque?

Write any two features of moving coil instrument

Write any two features of moving iron instrument

What is meant by creeping?

Convert (100001110.010)2 to decimal.

Give that (79)10 = (142)b determine the value of b.

Perform the arithmetic operations 35+40 and (-3.5)+(-40) with binary number in signed 2’s complement representation.

Convert (342.45)10 to binary and Octal.

Perform the following arithmetic operation using 1’s complement scheme. (4-8) ,(8-4) ,(-2-3)

Convert the following: (369)10 =( )8 =( )16 =( )2.

How many bits are required to represent the decimal numbers in the ranges from 0 to 999 using straight binary code? Using BCD codes?

Explain how addition and subtraction can be performed with 1’s complement and 2’s complement representations with suitable examples.

State de-Morgan’s Law.

Why NAND gate is called as an universal gates?

Write the dual of AB+ĀC+BC

Realize XOR function using only NAND gates.

How do you implement y=A+B using a 3 input OR gate?

Define distributive law.

What is mean by duality in Boolean Algebra?

Simplify the following function using algebraic method.

a) F=C(B+C)(A+B+C)

Implement AND and OR using NAND and NOR gates.

Give the truth table for JK flip-flop?

Name the problem associated with the asynchronous counter.

What is an universal shift register?

Draw MOD-8 Ripple counter using JK flip-flop and give the timing diagram

Give the excitation table for JK flip-lop.

Draw a MOD-6 counter using feedback counter.

Draw the timing diagram for a 3 stage ring counter.

How do you construct D flip-flop and T Flip-lop using JK flip-flop.

Distinguish between Synchronous and asynchronous counter.

Draw the circuit of serial n and serial out shift register and explain its operation.

Name the two problems that may arise in the ripple counter.

Draw the circuit of up-down counter and explain its working.

What is mean by the term edge triggered?

Describe the operation of BCD counter.

Draw the logic for 4-stage ring counter using JK flip-flo0p?

Define the hold time requirement of a clocked FF?

Show the T flip-flop implementation from S-R flip-flop?

Give the logical expression for sum and carry for a Half adder.

Obtain the expression for SUM and CARRY outputs of a full adder and implement the same.

Draw the block diagram of a communication system and explain its operation.

Explain briefly some of the telecommunication services.

Distinguish between telegraphy and telephony.

What is facsimile? how does it work?

What are the different transmission paths for communication?

What is the difference between analog and digital signals?

What is modulation?

Explain briefly the need for modulation.

What are the types of analog modulation ?

Write down a general expression for AM wave.

Write the expression for modulation index in AM .

Write down the mathematical expression for a FM wave.

What is advantage of a FM over AM?

Compare FM and PM.

State sampling theorem.

Define the following terms:

a) Pulse Width Modulation(PWM)

b) Pulse Amplitude Modulation(PAM)

c) Pulse Time Modulation (PTM)

d) Pulse Code Modulation (PCM)

Compare PAM and PWM.

Describe briefly some digital modulation schemes.

Define and describe pulse – position modulation.

What is pulse width modulation ?What other names does it have?

What is meant by Frequency-Shift Keying?

Differentiate FSK from PSK

What is back emf?

Why a dc series motor cannot be started on no load?

What are the various types of dc motors?

What is the necessity of a starter for a dc motor?

What is torque?

What is speed regulation?

What is called armature torque?

What is called shaft torque?

Draw the characteristics curve of a dc shunt motor?

What is the difference between three point and four point starters?

What is the method available for testing dc series motor?

Name the protective devices used in a 3point starter?

Mention the methods of speed control for a dc motor?

What are the losses that occur in a dc motor?

What are the various types of dc generators?

Draw the internal and external characteristic curves of dc shunt generator?

Draw the internal and external characteristic curves of dc series generator?

Draw the characteristics curves of dc compound generator?

DC series generators are suitable for ?

What is the function of commutator in DC generator?

What is the function of carbon brushes in DC generator?

What is called voltage regulation?

Write short notes on efficiency of a DC motor?

How the voltage builds up in Dc generator?

Why the armature core is made by laminated sheets?

Explain the construction and working principle of D.C. generator with neat diagram. (16)

Explain the different types of D.C. generators. (16)

Draw and explain the characteristics of different types of d.c.generators. (16)

a). Derive the emf equation of D.C. Generator. (8)

Sketch and explain the speed-current, speed-torque and torque-current characteristics of a shunt motor, series motor and compound motor. (16)

Draw the characteristic curves of D.C. shunt, series and compound motors. Use these curves to explain the applications for which these motors are used. (16)

a) List all the important parts of a D.C. Motor and explain the importance of each..a)Calculate the emf generated by 4 pole wave wound generator having 65 slots with 12 conductors per slot when driven at 1200 rpm. The flux per pole is 0.02 wb. (8)

A 4 pole lap wound dc shunt generator has a useful flux per pole of 0.07wb. The armature winding consists of 220 turns, each of 0.004 ohm resistance. Calculate the terminal voltage when running at 900 rpm if the armature current is 50A. (16)

Explain the principle of working a 1f transformer?

Discuss the difference between core type and shell type construction?

What is KVA rating of a transformer?

Draw the no load phasor diagram of a transformer?

Draw the phasor diagram of a transformer under load condition?

Explain voltage regulation?

Derive the emf equation of a transformer?

What is meant transformation ratio?

How the transformers are classified?

Write short notes on autotransformer.

Derive the condition for maximum efficiency?

What are the various losses that must be present in a transformer?

Explain the construction and working principle of single-phase transformer.(16)

Enumerate the various types of transformer. (4)

Derive an expression for the emf of an ideal transformer winding. (6)

Draw and explain the no load phasor diagram for a single-phase transformer. (6)

What is KVA rating of a transformer? (8)

Explain various features of an ideal transformer. (8)

b)The no load current of a transformer is 10A at a power factor of 0.25 lagging, when connected to 400v,50Hz supply, calculate(i)magnetizing component of no load current(ii) iron loss and(iii) maximum value of the flux in the core. Assume primary winding turns as 500. (8)

What is the frequency of induced emf of an induction motor?

Why squirrel cage induction motors are common in the domestic pump sets?

Distinguish between squirrel cage & slip ring induction motor?

What are the applications of induction motors?

Name the speed control methods of a 3 induction motors?

Define a slip of an induction motor?

What is called synchronous speed?

Define electron volt?

State the relationship between electric field intensity, and potential?

An electron beam from rest is accelerated by a potential of 200V. Find the final velocity of the electron?

List out the common diode applications?

Define zener breakdown?

Differentiate photodiode and light emitting diode.

Explain the forward and reverse bias operation and VI characteristics of a PN Junction diode. (16)

a)Derive the diode current equation? . (8)

b)Discuss the current components of PN junction diode? (8)

a)Explain any two applications of diode with neat diagram . (8)

Define pinch - off voltage?

Derive the relation between pinch - off voltage & drain current?

What is a MOSFET?

What is a MESFET?

Explain the operation of PNP & NPN transistor? (12)

b). What is transistor? State its types

Compare CE – CB – CC Configuration? (8)

a). Explain the input & output characteristics of CE configuration of a transistor?

State FET& its types? (4)

a)Explain the input & output Characteristic of CB configuration of a transistor?

Explain the construction & characteristics of JFET

What is a rectifier?

Explain the operation & characteristics of TRIAC?

Explain the operation & characteristics of UJT?

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