final beee qb

Subject Code / Name: GE6252/ BASIC ELECTRICAL & ELECTRONICS ENGINEERING

UNIT – I ELECTRICAL CIRCUITS & MEASURMENTS

PART – A1. State Kirchoff’s voltage and current law. (AU 2013)

Kirchoff’s current lawThe sum of currents flowing towards the junction is equal to the sum of thecurrents flowing away from it.Kirchoff’s voltage lawIn a closed circuit, the sum of the potential drops is equal to the sum of thepotential rises.

2. State the different type of instruments based on their operating principles. (AU 2013) a.Permanent magnet moving coil(PMMC) instrument b.Permanent magnet moving iron (PMMI) instrument c.Dynamometer type wattmeter d.Energy meter

3. What are the advantages of electromechanical measuring instruments? (AU 2012)1. Operating current is small.2. Sensitivity is high.3. Consumes less power.4. Can cover wide range.

4. Define: Power factor. (AU 2012)The power factor is the cosine of the phase angle between voltage and current.

cosФ =ResistanceImpedance ; cosФ =

5. Distinguish between a mesh and a loop a circuit (AU 2011)Mesh Loop

Should have closed path. Should have closed circuit.Same current flows through entire circuit. Current may varely.

6. What is RMS value of a periodic current? (AU 2011)It is the mean of the squares of the instantaneous value of current over oneComplete cycle.

7. Define form factor. (AU 2010)The ratio of RMS value to the average value is called form factor.Form factor (Kf) = RMS value / Average value

8. State the principle of Moving Iron Repulsion Instrument. (AU 2010)Repulsion type instruments have two vanes inside the coil, the one is fixed and another is movable. When the current flows in the coil, both the vanes are magnetised with like polarities induced on the same side, Hence

KCE/CIVIL&MECH/QB/I YR/BEEE


due to the repulsion of like polarities , there is force of repulsion between the two vanes causing the movement of the moving vane.

9. What are the components of an electric circuit? (AU 2009)1. Resistor2. Capacitor3. Inductor4. Voltage source

10. Compare active and passive elements. (AU 2009)

Active elements Passive elementsThe sources of energy are called active elements.

The element which stores or dissipates the energy is called passive elements.

Example: Voltage source, Current source Example: Resistor, Capacitor, Inductor

PART B

2. (i)For the circuit diagram shown below, calculate the line current, the power and the power factor. The value of R,L,C in each phase are 10Ω,1H and 100µF respectively.(8)

(ii)Explain the principle of operation of attraction type and repulsion type of moving iron instruments with neat sketches.(8)

(AU 2013)

3. (i) Determine the line current, power factor and total power when a 3-phase 400V supply is given to a balanced load of impedance (8+j6)Ω in each branch, is connected in star.(8)(ii) With the help of a neat diagram, explain the construction and operation of an induction type energy meter. (8)

(AU 2012)

4. Three similar coils connected in star, take a power of 1.5KW at a power factor of 0.2 tagging from a 3phase, 400V, 50Hz supply. Calculate the resistance and inductance of each coil.

(AU 2012)

6.Elaborate in detail about moving iron ammeters and voltmeters with neat diagrams. (AU 2011)

7. Define the following terms.(i) Active power (4)(ii) Reactive power (4)(iii) Apparent power (4)(iv) Power factor (4)

(AU 2011)

8. A bridge circuit ABCD has RAB = 2Ω, RBC = 3 Ω, RCD = 40 Ω, RDA = 1 Ω, RBD = 5 Ω. A battery of 5 V with negligible internal resistance is connected between the terminals A and C. Determine the current in each branch.

(AU 2010)

10.Explain briefly about dynamometer type wattmeter? Derive the torque equation and give its error.

(AU 2009)

UNIT – IIELECTRICAL MECHANICS

PART – A1. What is the purpose of yoke in a dc machine? (AU 2012)

1. It provides mechanical support for the poles and acts as a protecting cover for the whole machine.



2. It carries the magnetic flux produced by the poles.2. What are the types of transformers based on construction? (AU 2012)

1. Core type transformer2. Shell type transformer3. Berry type transformer

3. Sketch the circuit diagram for separately excited dc generator. (AU 2011)

4. What is the transformer? (AU 2010)Transformer works on the principle of mutual induction. It transfer an electric energy from one circuit to other circuit when there is no electrical connection between the two circuits.

5. What is back emf? (AU 2010)The induced emf is always acts in the opposite direction of the supply voltage(according to the Lenz’s law).This emf always opposes the supply is called Back emf.

Eb = Volts.

6. What is the voltage equation for the motor? (AU 2009)

V = Eb + IaRaV applied voltageEb back e.m.fIa Armature currentRa Armature resistance

7.What is emf equation for transformer?

(AU 2009)

E = 4.44 f NФWhere E = Induced emf F = supply frequency N = Number of turns

Ф = Maximum flux in core

7. What is leakage flux? (AU 2010)The flux which is not linking with the main flux is called leakage flux.

8. List out the major parts of the DC machine. (AU 2011)1. Field system2. Armature core3. Armature winding4. Commutator5. Brushes

9. Define slip. (AU 2010)The difference between the synchronous speed and rotor speed is known as slip.



S = Ns – NWhere S = slip Ns = synchronous speed N = Rotor speed

10. Why the single phase induction motor is not self starting? (AU 2010)The single phase induction motors are not self starting because the torque produced for a applied sinusoid current is zero. To make it self starting split phase arrangement is provide.

PART B

1. (i) Derive the emf equation of DC generator.(8)(ii)A short shunt cumulative compound DC generator supplies 7.5KW at 230V.The shunt field, series field and armature resistances are 100.0.3, 0.4Ω respectively. Calculate the induced emf and the load resistance.(4)(iii)A 30KW, 300V, DC shunt generator has armature and field resistances of 0.05Ωs & 100Ω respectively. Calculate the total power developed by the armature when it delivers full output power.(4)

(AU 2013)

2. (i)A single phase 2200/250V,50Hz transformer has a net core area of 36cm^2 and maximum flux density of 6Weber/m^2.Calculate the number of primary and secondary turns.(4)(ii)with the help of neat sketches, explain the construction and operating principle of split phase induction motors.(12)

(AU 2012)

3. (i)Draw the circuit diagram of the following three types of DC motors and write the relationships among the currents and voltages:(1)Separately excited motor(2)series motor(3)shunt motor.(6)(ii)Explain the characteristics of a Dc shunt motor. Sketch the graphical representation of the concerned characteristics.(6)(iii)A DC motor connected to a 460V supply has on armature resistance of 0.15Ωs.Calculate (1)The value of back emf when the armature current is 120A.(2)The value of armature current when the back emf is 447V.(4)

(AU 2012)

4. (i)Explain the construction and working principle of capacitor start and capacitor run single phase induction motor. What are its advantages and practical applications?(8)(ii)Explain the principle of operation of single phase transformer.(8)

(AU 2012)

5. (i)Derive the emf equation of the DC generator.(8)(ii) With neat diagram, explain the working of separately excited DC generator.(8)

(AU 2011)

6. Explain the principle of operation of ideal transformer and derive its emf equation. (AU 2011)7. (i)Explain with a neat sketch, DC motor construction.(8)

(ii)Give the application of DC motor construction.(8)(AU 2011)

8. (i) A shunt generator supplies a load of 7.5kW at 200V. Calculate the induced emf if armature resistance is 0.6Ω and field resistance is 80Ω.(ii) Derive the emf equation for DC machine.

(AU 2010)

9. The open circuit (O.C) and short circuit (S.C) test results on a single phase,50Hz 250/500 volts transformer are as:O.C. test (L.V. side): 250 volts, 0.9 Amp, 45watsS.C. test (H.V. side): 25 volts, 12 Amp, 100 wats.Calculate the efficiency and approximate regulation While supplying 8Amps at 500 volts at 0.8 power factor lagging.

(AU 2009)

10. A DC shunt generator supplies a load of 7.5kW at 200V. Calculate the induced emf if armature resistance is 0.6Ω and field resistance is 80Ω.

(AU 2009)

UNIT – III SEMICONDUCTOR DEVICES AND APPLICATIONS

PART – A

1. Write the difference between the PN junction diode and zener diode. (AU 2013)

PN Junction Zener diodeDiode can conduct only in one direction

Zener diode allows the conduction in both directions.

A normal doode will be permanently It does not get damaged like PN



damaged for large reverse current diode.Used for rectification. Used in voltage regulation.

2. Give the biasing condition for a transistor to operate as an amplifier. (AU 2013)Baising conditions for a transistor to operate as an amplifier.

(i) The emitter-base function must be forward biased and the collector base junction must be reversed biased.

3. Define peak inverse voltage of a PN junction diode. (AU 2012)Peak inverse voltage or peak reverse voltage is the maximum voltage that a diode can withstand in the reverse direction without breaking down or avalanching. If this voltage is exceeded the diode may be destroyed.

4. Define: Current amplification factor for CE configuration in transistors. (AU 2012)

= β β reveals the relative magnitude of one current with respect to other. It is the ratio of the DC collector current to the DC base current in forward active region. It ranges from about 50 to 400.

5. State the advantages of bridge rectifier. (AU 2011)1. Rectification efficiency of a full wave rectifier is double as compared to half wave rectifiers.2. Full wave rectifiers can supply a large load current as compared to half wave rectifiers.3. Half wave rectifier requires only one diode and is less costly.4. Full wave rectifier circuits have better voltage regulation as compared to half wave rectifiers.

6. State what is “Early Effect” in a transistor. (AU 2011)As the collector voltage VCC is made to increases the reverse bias, the space charge width between collector & base tends to increase, with the result that the effective width of the base decreases . This dependency of base – width on collector to emitter voltage is known as the Early Effect.

7. What is junction capacitance? (AU 2010)An applied reverse bias causes the majority carrier to move away from the junction, there by unrecovering the immobile charges, if this reverse voltage is increased, the thickness of the space charge region at the junction increases. This further increases the number of uncovered charge and result a capacitive effect. This is called junction capacitance.

8. What are the applications of a diode? (AU 2009)1. Rectifiers in the D.C power applier.2. Clamping circuit.3. PN diodes in demodulation circuits.4. Zener diodes in voltage regulators.

9.What are the basic conditions of the base-emitter and base-collector junction for a transistor to operate as an amplifier?

(AU 2009)

1.Base-emitter = Forward bias2.Base-collector = Reversed bias

10. What is mean by zener effect. (AU 2009)If a current carrying conductor is placed in a magnetic field an EMF is induced.

PART B

1. (i)Explain the mechanism of avalanche breakdown and zener breakdown.(8)(ii)with the help of relevant circuit and VI characteristics, show how a zener diode is used as a voltage generator.(8)

(AU 2013)

2. (i)Explain the operation of PNP transistor.(6)(ii)With neat sketch explain the input and output characteristics of a transistor in CB configuration. Draw also the necessary circuit.(10)

(AU 2013)

3. (i)With the help of VI characteristics describe the working principle of zener diode. What is its symbol? Mention also the special properties of zener diode when compared to ordinary diode.(8)(ii)What is half wave rectifier? Sketch its circuits. Discuss the operation of half wave rectifier with the help of necessary waveform.(8)

(AU 2012)

4. (i)Draw the three configurations of a bipolar junction transistor.(6) (AU 2012)



(ii)For a transistor connected in CE configuration, sketch the typical output and input characteristics.(10)

5. Explain the principle and operation of full wave rectifier. (AU 2012)6. Discuss briefly about the small signal amplifier. (AU 2011)7. What are the different terminals in a transistor? Draw the symbol of npn transistor and

explain its working.(AU 2011)

8. Draw the circuit diagram of a transistor amplifier and explain how it amplifies the input signal?

(AU 2010)

9. Compare CE, CB and CC transistor configurations.(i) In terms of input impedance, output impedance, current gain and voltage gain.(ii) Draw the output characteristics of CE configuration and mark its regions of operation.

(AU 2010)

10. Explain the operation of PN junction diode with its VI characteristics. (AU 2009)

UNIT – IV DIGITAL ELECTRONICS

PART – A

1. Draw the symbol of OR gate and its truth table. (AU 2009)

2. Convert the binary function 0.101 into decimal equivalent. (AU 2009)Decimal of (0.101)2=1 x 2-1 + 0 x 2-2 + 1 x 2-3 = (0.625)10

3. Realize the D latch using NAND gates. (AU 2009)

4. Write the truth table of EXCLUSIVE OR. (AU 2010)

5. Express the following binary number in its equivalent decimal numbers. (AU 2010)(a)10.01 (b) 101.11

Decimal of (10.01)2 = 1 x 21 + 0 x 20 + 0 x 2-1 + 1 x 22 = (2.25)10

Decimal of (101.11)2= 1 x 22 + 0 x 21 + 1 x 20 + 1 x 2-1 + 1 x 2-2 = (5.75)10

6. Name four different flip-flops commonly available. (AU 2011)



RS flip-flop

D flip-flop

JK flip-flop

T flip-flop

Master-slave JK flip-flop

7. What is decade counter? (AU 2011)A decade counter is one that counts in decimal digits, rather than binary. It counts from 0 to 9 and then resets

to zero.

8. Draw the symbol of AND gate and its truth table (AU 2011)

9. Mention the types of DAC.

Weighted resistor DAC

R-2R ladder DAC

Inverted ladder DAC

Multiplied DAC

(AU 2011)

10. What are universal gates? Why do we call them so? (AU 2012)Universal gates are NAND gate and NOR gate. NAND and NOR are the gates that can be used alone to

generate remaining gates such as NOT, AND and OR.

PART B1. Draw the logic diagram of a clocked master slave JK flip flop and explain its working (AU 2009)-3

2.Describe the operation performed by the following arithmetic circuits(i)Full adder, (ii) Half adder.

( AU 2009)

3. Draw the logic diagram of a 4 bit buffer register and explain its working. ( AU 2009)4. Explain with neat sketch the working of a successive approximation ADC. ( AU 2009)-25. Implementation of full adder circuit using NAND gates. ( AU 2009)6. From R-2R ladder network, explain the working principal of 8 bit DAC. Derive its resolution. ( AU 2009)

7.Draw the circuit of a binary weighted resistor digital to analog converter and explain its operation.

( AU 2010)-3

8.Draw and explain the circuit diagram of AND, OR, NOT, and NAND gates with suitable truth tables.

( AU 2011)

9. Draw the logic diagram and explain the working of a half adder. ( AU 2011)10. Explain the operation of RS flips flop and clocked RS flip flop. ( AU 2011)

11.Explain the operation of an asynchronous counter.

( AU 2011)

UNIT – V FUNDAMENTALS OF COMMUNICATION ENGINEERING

PART – A1. Define modulation. What are the different types of modulation? (AU 2009)

The process by which the baseband signal modifies the carrier signal is called modulation and the resultant signal is called modulated signal.Analog modulation:



Amplitude modulation

Angle modulation

Frequency modulation

Phase modulation

Pulse modulation: Digital modulation

Pulse code modulation

Analog modulation

Pulse amplitude modulation

Pulse duration modulation

Pulse position modulation

2. Define the term modulation index for frequency modulation. (AU 2009)Modulation in FM is generally expressed in terms of the modulation index. The modulation index is the ratio of the frequency deviation to the modulating frequency.

3. Define the term modulation index for amplitude modulation. (AU 2009)Modulation index is the ratio of amplitude of the modulating signal and amplitude of the carrier signals. It is also called modulation factor, modulation coefficient or the degree of modulation.

4. List any four advantages of FM over AM. (AU 2009) Amplitude of FM wave is constant

FM reception is more immune to noise than AM reception

In FM, all the transmitted power is useful

FM operates in VHF and UHF range, the propagation is line of sight propagation by space

wave

5. State any two differences between analog and digital signals. (AU 2010)ANALOG SIGNAL DIGITAL SIGNAL

Analog signal is Continuous in both

time and amplitude.

Digital signal is discontinuous.

It represents some physical quantity

such as sound, light, temperature,

position or pressure and they are a

MODEL of the real quantity.

It has two amplitude levels such as high

or low.

6. What are the applications of microwave? (AU 2010) Heating

Communication

7. Define the term demodulation. (AU 2010) At the receiving end, the baseband signal and the carrier signal are separated from modulated

signal by the process of demodulation.

8. Sketch the block diagram of basic communication system (AU 2011)



9.Mention two advantages of modulation when compared to transmission of unmodulate signal.

(AU 2012)

Reduces the height of antenna

Avoids mixing of signals

Increases the range of communication

10. What is the basic function of communication satellite? (AU 2012)

Communication satellite receives the microwave signal from transmitter on the earth. It amplifies

the received signals and sends them back to the earth.

PART B1. Explain the need for modulation. (AU 2009)

2.Draw the block diagram of radio broadcasting and reception system and explain the function of each block.

(AU 2009)

3. Draw the circuit diagram of balanced modulator and explain its operation (AU 2009)4. Explain the principle of operation of FAX. (AU 2009)

5.With a neat diagram, explain the operation of amplitude modulation. Derive its power relations.

(AU 2009)

6. Explain satellite communication system. (AU 2009)7. Write a detailed note on optical fibre communication. (AU 2010)8. Make comparison of analog and digital signals characteristics. (AU 2010)

9.Describe about frequency modulation. Obtained the mathematical representation of frequency modulated wave and explain modulation index.

(AU 2010)

10. With help of suitable block diagram, explain the various functional blocks of TV transmitter. (AU 2010)

11.Describe the satellite communication system, with the help of block diagrams of earth- station transmitter and earth-station receiver.

(AU 2010)


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