code no: r21026 r10 set - 1 ii b. tech i semester ... ece-all.pdf... a 4 -pole, lap wound, d.c...

||''''|||''|'''||''|

Code No: R21026

II B. Tech I Semester Supplementary Examinations, June - 2015

ELECTRONIC DEVICES AND CIRCUITS (Com. to EEE, ECE, EIE, ECC, CSE, IT, BME)

Time: 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry Equal Marks

~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Explain in detail about Magnetic Deflection in cathode ray tube.

b) The electron beam in a CRT is displaced vertically by a magnetic field of flux density

2 x 10-4

Wb/m2 .The length of the magnetic field along the tube axis is the same as that

of electrostatic deflection plates. The final anode voltage is 800v.Calcualte the voltage

whichshould be applied to the Y- deflection plates 1cm apart , to return the spot back to

centre of screen. (7M+8M)

2. a) Prove that the conductivity of a semiconductor is given by σ= q( p µp + n µp)

b) Define the terms conductivity and mobility in a semiconductor. (7M+8M)

3. a) Draw the V-I Characteristic of Zener diode and explain its operation.

b) Explain Avalanche breakdown and Zener break down . (7M+8M)

4. a) Obtain the ripple factor of a Full wave rectifier with shunt capacitor filter.

b) Compare the performance of inductive L-section and π-section filters. (7M+8M)

5. a) Define α, β and γ of a transistor show how are they related to each other?

b) Explain how a transistor is used an amplifier. (7M+8M)

6. a) Explain the characteristic parameters of the JFET

b) A JFET has a driven current of 4mA.If Dss = 8mA and Vgs(off)= - 6V. find the values of

Vgs and Vp. (10M+5M)

7. a) Explain in detail about Bias compensation method

b) Explain in detail about collector to base bias. (7M+8M)

8. a) Derive the network parameters for Two port devices.

b) What are salient features of Hybrid Parameters? (7M+8M)

1 of 1

SET - 1 R10

||''''|||''|'''||''|

Code No: R21026






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Explain in detail about electrostatic deflection in cathode ray tube.

b) An electrostatic CRT has a final anode voltage of 600V. The deflection plates are 3.5cm

long and 0.8 cm apart. The screen is at a distance of 20cm from the center of plates. A

voltage of 20V is applied to the defection plates.

Calculate i) Velocity of electron on reaching the field.

ii) Acceleration due to deflection field.

iii) Deflection produced on the screen in cm.

iv) Deflection sensitivity in cm/v. (5M+10M)

2. a) Explain the difference between intrinsic and extrinsic semiconductor

b) What is meant by p-type impurity in a semiconductor? (8M+7M)

3. a) Draw the V-I Characteristic of PN junction diode and explain its operation.

b) Show that the Zener diode can be used as a voltage regulator. (8M+7M)

4. A Half wave rectifier has a load of 3.5kΩ , If the diode resistance and secondary coil resistance

together have a resistance of 800Ω and input voltage has a signal voltage of peak value 240V

calculate i) Peak , average and rms valve of current flowing ii) dc power output

iii) ac power input iv) efficiency of the rectifier. (15M)

5. a) Explain the input and output Characteristic of a transistor in Common Emitter Configuration

b) Explain about punch through. (10M+5M)

6. a) With the help of suitable diagrams explain the working of different types of MOSFET.

b) Compare the MOSFET with JFET. (10M+5M)

7. a) Explain in detail about operating point and Basic stability

b) Explain in detail about compensation against variation in VBE , ICO. (8M+7M)

8. a) Why Hybrid parameters are called so? Define them.

b) A CE amplifier has the h-parameters given by hie = 1000Ω,hre = 2 x 10-4

, hfe =50

and hoe =25µ mho. If both the load and source resistance are 1k Ω, Determine the

i) Current gain ii) Voltage gain (7M+8M)

1 of 1

SET - 2 R10

||''''|||''|'''||''|

Code No: R21026






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Explain about in magnetic field.

b) A charged particle having charge thrice that of an electron and mass twice that of an electron

is accelerated through a potential difference of 50V before it enters a uniform magnetic

field flux density of 0.02 Wb/m2 at an angle of 25

o with field.

Calculate i).The velocity of the charged particle before entering the field.

ii). Radius of the helical path

iii) Time of revolution. (5M+10M)

2. a) Explain about Fermi Level in between intrinsic and extrinsic semiconductor.

b) define Drift and diffusion currents in semiconductor. (8M+7M)

3. a) Explain the principle behind the Varactor diode and list out its applications.

b) Explain the Construction of a PIN diode and give the applications of PIN diode. (7M+8M)

4. a) Explain about series and shunt voltage regulators.

b) Derive an expression for the ripple factor in a full wave rectifier using inductor filter.

(7M+8M)

5. a) A transistor has IB = 100µA and IC = 2µA Find

i) β of the transistor ii) α of the transistor iii) Emitter current IE

iv) if IB changes by +25µA and IC changes by +0.6mA. Find the new valve of β?

b) Explain about Photo Transistor. (5M+10M)

6. a) Describe the working principle of an SCR with V-I Characteristics.

b) Briefly describe some applications of JFET. (10M+5M)

7. a) Explain in detail about Stabilization factors.

b) Explain about Thermistor and Sensistor compensation. (7M+8M)

8. a) Explain about Conversion formulas for the parameters of three transistor configuration

b) Explain in detail about Measurement of h-parameters (7M+8M)

1 of 1

SET - 3 R10

||''''|||''|'''||''|

Code No: R21026






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Explain about Two – Dimensional motion of electron.

b) Explain in detail about Magnetic Focusing. (7M+8M)

2. a) Discuss the following with respect to semiconductor

i) doping ii) Dopant iii) donor iv) acceptor.

b) Explain “Majority and minority carriers” in semiconductors. (8M+7M)

3. a) What is tunneling? Form the energy band diagram explain the V-I characteristic of a

tunnel diode.

b) List out the applications of tunnel diode and mention its advantages and disadvantages.

(10M+5M)

4. a) Draw the circuit diagram of an Half wave rectifier and explain its operation

b) Show that a Full wave rectifier is twice as efficiency as a Half wave rectifier. (8M+7M)

5. a) Explain the input and output Characteristic of a transistor in Common Base Configuration.

b) The Common Base d.c current gain of a transistor is 0.967 .If emitter current is 10mA,

What is the value of base current? (10M+5M)

6. a) Describe the working principle of an UJT with V-I Characteristics.

b) Explain why an SCR is operated only in the forward biased condition. (8M+7M)

7. a) Explain about Self Bias Amplifiers.

b) Explain about Thermal runaway and Thermal stability. (8M+7M)

8. a) Explain in detail about analysis of a transistor amplifier circuit biasing h - parameters.

b) Explain about Transistor Amplifier configurations. (7M+8M)

1 of 1

SET - 4 R10

||''''|||''|'''||''|

Code No: R21041


ELECTRICAL TECHNOLOGY (Com. to ECE, EIE, BME)




~~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) State and explain Fleming’s right hand thumb rule. [5]

b) Derive from first principles an expression for the emf of a DC generator.

[10]

2 a) How is a shunt motor started? Why it should not be started direct on line? [6]

b) A 4-pole, lap wound DC motor has 540 conductors. Its speed is found to be

1000rpm.the flux per pole is 25mWb. It is connected to 230 Volts dc supply.

Armature resistance Ra is 0.8Ω. Calculate induced emf and armature current.

[9]

3 a) Derive an emf equation of a single phase transformer. [7]

b) The maximum flux density in the core of 250/300V, 50Hz single- phase

transformer is 1.2 tesla. If the emf per turn is 8V. Determine primary and

secondary turns and area of core.

[8]

4 The following data were obtained on a 20kVA, 50 Hz, 2000/200V distribution

transformer:

Voltage (V) Current (A) Power (W)

OC test with HV open-circuited 200 4 120

SC test with LV short circuited 60 10 300

Draw the approximate equivalent circuit of the transformer referred to the HV

and LV sides respectively.

[15]

5 a) What are the advantages of three-phase induction motors over single-phase

motors? Also list their applications.

[8]

b) Draw and explain the torque-slip characteristics of an induction motor.

[7]

6 What is an alternator? Explain its principle of operation. With a neat diagram,

explain the constructional features of a three-phase alternator.

[15]

7 a) What are different types of single phase induction motors? [6]

b) Explain the operation of a capacitor start, capacitor run induction motor.

[9]

8 a) Define and explain Deflecting torque, Controlling torque and Damping torque. [8]

b) Compare between moving coil and moving iron instruments. [7]

1 of 1

SET - 1 R10

||''''|||''|'''||''|

Code No: R21041






~~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) What are the types of DC generators? List their applications. [7]

b) A 4-pole, lap wound, d.c machine has total number of 800 armature

conductors and produces 0.03 Wb flux per pole when field is excited. If the

machine is driven by a prime mover at 1000 rpm, calculate the generated emf

across the armature.

[8]

2 a) What is back emf? Explain the significance of back emf. [6]

b) A 10 kW, 250V, DC shunt motor with an armature resistance of 0.8 and a

field resistance of 275 takes 3.91A, when running at no-load at rated voltage

and rated speed. Calculate the machine efficiency as a generator when

delivering an output of 10kW at rated voltage and speed; and as a motor

drawing an input of 10kW.

[9]

3 a) Discuss the principle of operation of a single-phase transformer. [7]

b) What are different types of single-phase transformers? Explain its

constructional features.

[8]

4 The efficiency of a 1000 kVA, 110/220V, 50Hz, single-phase transformer is

98.5% at half full-load at 0.8 pf leading and 98.8% at full-load upf.

Determine: i) iron loss , ii) full-load copper loss, and iii) maximum efficiency

at upf.

[15]

5 a) List and explain different types of induction motors. Mention few applications

of induction motors.

[7]

b) Explain the rotor resistance starting scheme for a slip-ring induction motors.

[8]

6 a) Define and explain pitch factor and distribution factor. [6]

b) Derive the expression for emf induced in an alternator.

[9]

7 a) What are different application of single-phase induction motors [6]

b) Explain in detail the operation of a shaded-pole single-phase induction motor.

[9]

8 With a neat diagram, explain the operation of a permanent magnet moving

coil instruments. Also mention its applications.

[15]

1 of 1

SET - 2 R10

||''''|||''|'''||''|

Code No: R21041






~~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) Explain with a neat sketch, the constructional details of a DC machine. [9]

b) A DC generator is found to develop an armature voltage of 200 V. If the flux

is reduced by 25% and speed is increased by 40%, calculate the armature

generated voltage.

[6]

2 a) What are different losses that occur in a DC motor? Explain briefly. [6]

b) A 4-pole DC motor is lap-wound with 400 conductors. The pole shoe is 20 cm

long and average flux density over one-pitch is 0.4T, the armature diameter

being 30 cm. Find the torque and gross mechanical power developed when the

motor is drawing 25A and running at 1500 rpm.

[9]

3 a) With a phasor diagram, explain the operation of a single phase transformer on

no-load condition.

[7]

b) Define and explain the terms: step-up transformer, step-down transformer,

ideal transformer and isolated transformer.

[8]

4 What are different losses that occur on a transformer? Explain the conduction

of open-circuit and short-circuit tests on transformers.

[15]

5 List and explain in detail different starting methods for a three-phase

induction motor.

[15]

6 a) What are different types of alternators? [5]

b) A 3-phase, 16 poles alternator has a star-connected winding with 144 slots and

10 conductors per slot. The flux per pole is 0.03 Wb, sinusoidally distributed

and the speed is 375 rpm. Find the frequency of generated voltage, the

magnitude of phase voltage and lone voltage. Assume full-pitched coil.

[10]

7 a) Explain the working of an AC servomotor. Also list their applications. [8]

b) What are stepper motors? List different types of stepper motors.

[7]

8 a) List the advantages and limitation of permanent magnet moving coil

instruments.

[7]

b) A PMMC instrument has a coil resistance of 100Ω and gives a fullscale

deflection (FSD) for a current of 500 µA. Determine the value of shunt

resistance required if the instrument is to be employed as an ammeter with a

FSD of 5A.

[8]

1 of 1

SET - 3 R10

||''''|||''|'''||''|

Code No: R21041






~~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) What is residual magnetism? Explain its use. [6]

b) A 4–pole, lap wound 750 rpm DC shunt generator has an armature resistance

of 0.4Ω and field resistance of 200Ω. The armature has 720 conductors and

the flux per pole is 30m Wb. If the load resistance is 15Ω, determine the

terminal voltage.

[9]

2 a) Discuss a scheme to control the speed of a DC motor above its rated speed. [7]

b) Explain the operation of the three point starter with neat sketch.

[8]

3 a) What is a transformer? Differentiate between a core-type and a shel-type

transformer.

[8]

b) State and prove the condition for maximum efficiency of a transformer.

[7]

4 A 100KVA, 1-phase transformer has full load primary current of 400A and

total resistance referred to primary is 0.006. If the iron loss amounts to 500W,

find the efficiency at full load and half load at

i) Unity power factor

ii) 0.8 power factor.

[15]

5 a) Compare between Slip ring and Squirrel cage induction motors. [9]

b) Define and explain the terms: slip and slip speed of an induction motor.

[6]

6 What is regulation? Explain the predetermination of regulation of an alternator

by Synchronous Impedance Method

[15]

7 a) What is a tachometer? Explain the operation of AC tachometer. [8]

b) What is a synchro? What is the primary purpose of a synchro system? What

are the two major components of a synchro?

[7]

8 Explain in detail the construction and basic principle operation of Moving-

iron Instruments. Also mention its applications.

[15]

1 of 1

SET - 4 R10

||''''|||''|'''||''|

Code No: R21022


MANAGERIAL ECONOMICS AND FINANCIAL ANALYSIS (Com. to EEE, ME, ECE, EIE, CSE, IT, ECC, BME)




~~~~~~~~~~~~~~~~~~~~~~~~~~

1. a) “Managerial Economics is the integration of economic theory with business practice for

the purpose of facilitating decision making and forward planning by management”.

Explain?

b) Define demand and describe its determinants with suitable examples?

2. a) Differentiate between the following:

i) Point Price elasticity of demand and Arc Price elasticity of demand

ii) Elasticity of demand and elasticity of supply

b) Write briefly about trend projection method?

3. a) What is the relationship between firm’s short run production function and its fixed and

variable costs?

b) Distinguish between:

i) Implicit and Explicit costs

ii) Accounting and Economic costs

4. a) What are the features of Perfect competition?

b) Distinguish between Market skimming pricing and penetrating pricing.

5. a) What are the features of Joint stock Company?

b) Write short note on features of Business cycles.

1 of 2

R10 SET - 1

||''''|||''|'''||''|

Code No: R21022

6. The following are the balances extracted from the books of Rakesh on 31st March 2015.

PARTICULARS AMOUNT (IN RUPEES)

Rakesh Capital 30,000

Rakesh Drawing 5,000

Furniture and Fixtures 2,600

Opening Stock 22,000

Debtors 18,000

Rent from tenants 1,000

Purchases 1,10,000

Sales 1,50,000

Electricity Charges 1,100

Sales return 2,000

Discounts (Dr) 1,600

Bank Overdraft 4,200

Creditors 13,800

Discount (Cr) 2,000

Taxes and Insurances 2,000

General Expenses 4,000

Salaries 9,000

Commission (Dr) 2,200

Carriage on purchases 1,800

Bad debts 800

Adjustments:

Closing stock at the end was Rs 20,060; Depreciate furniture and fixtures by Rs 550.

Prepare Trading, Profit and Loss account and Balance Sheet for the year ended 31st March

2015 after taking the above adjustments.

7. From the following particulars you are required to prepare a statement of proprietary fund:

Capital turnover ratio=2; Fixed Asset turnover ratio=4; Gross profit turnover ratio=20%; Stock

velocity=5; Debtors velocity= 3 months; Creditors velocity is 2.5 months. The gross profit is

Rs 50,000,Reserves and Surplus is Rs 15000 and closing stock was Rs 5000 lesser than

opening stock.

8. Explain briefly the various methods of capital budgeting.

2 of 2

R10 SET - 1

||''''|||''|'''||''|

Code No: R21022






~~~~~~~~~~~~~~~~~~~~~~~~~~

1. What do you understand by Elasticity of demand? How do you measure it? What is its

significance?

2. Explain and illustrate the following: and also mention why they arise: a) The Law of Constant

Returns b) The Law of increasing returns.

3. What is opportunity Cost? Give some examples of opportunity cost. How are these costs

relevant for managerial decisions?

4. What is a Market? Explain, in brief, the different Market structures.

5. Explain the merits and demerits of different forms of Business organization and their suitability

with different types of business Activities

6. What are the accounting concepts that govern accounting process? Explain in brief.

7. The following are the extracts from the financial statements of Marvel Ltd. as on 31st March

2014 and 31st March 2015 respectively

31st March 2014

( Amount in Rupees)

31st March 2015

( Amount in Rupees)

Stock 10,000 25,000

Debtors 20,000 20,000

Bills receivable 10,000 5,000

Cash 18,000 15,000

Bills payable 15,000 20,000

Bank Overdraft 2,000

9% Debenture 5,00,000 5,00,000

Sales 3,50,000 3,00,000

Gross Profit 70,000 50,000

Compute Current ratio, Acid test ratio and Stock Turnover ratio and also interpret the result.

8. Compare and contrast with illustration

Accounting rate of return and Payback period method

Net present Value and IRR method

1 of 1

R10 SET - 2

||''''|||''|'''||''|

Code No: R21022






~~~~~~~~~~~~~~~~~~~~~~~~~~

1. Define Managerial Economics. Explain the nature and scope of managerial economics?

2. What is meant by Elasticity of demand? What are the factors governing the potential demand

for a product as either Elastic or Inelastic?

3. Explain how production function is valuable to manufacturer?

4. What are the features of perfect competition? Explain with the help of a diagram how price

output is determined in perfect competition?

5. Define and evaluate partnership form of business organization.

6. What is working capital? What are the factors governing working capital requirement?

Illustrate.

7. Ram Enterprise is considering purchasing a CNC machine. The following are the earnings after

tax from the two alternative proposal under consideration each costing Rs 8,00,000. Select the

better proposal if the company wishes to operate @ 10% rate of return

Year 1 Year 2 Year 3 Year 4 Year 5

Proposal I 80,000 2,40,000 3,20,000 4,80,000 3,20,000

Proposal 2 2,40,000 3,20,000 4,00,000 2,40,000 1,60,000

Present value of Rs 1 @10% 0.909 0.826 0.751 0.683 0.620

8. Journalize the following transactions and post them to ledger.

i) Ram invested Rs 10,000 in cash

ii) He bought goods worth Rs 2000 from Shyam

iii) He bought a machine for Rs 5000 from Lakshman on account

iv) He paid to Lakshman Rs. 2000

v) He sold goods for cash Rs. 3000

vi) He sold goods to A on account for Rs 4000

vii) He paid to Shyam Rs. 1000

viii)He received amount from A Rs. 2000.

1 of 1

R10 SET - 3

||''''|||''|'''||''|

Code No: R21022






~~~~~~~~~~~~~~~~~~~~~~~~~~

1. a) What do you understand by demand? What are the different types of demand

b) State the law of demand what its exception are

2. How do you forecast demand for product and services? Explain the method of least squares as a

method of forecasting demand.

3. Do you think monopoly is present in the current business environment? Explain how price

output is determined in monopoly in short run

4. Rahim sells 500 kg of sweets per hour at a rate of Rs 100 per kg. The fixed overhead is Rs 7000

and the variable cost is Rs 25 per kg. There is a proposal to reduce the price by 10%.Calculate

the present PV and present BEP both in units and in Rupees; present level of profit and future

PV ratio and BEP both in units and in Rupees. How many kilograms must be sold to earn

present level of profit?

5. Explain any four pricing methods based on strategy.

6. Based on the following information of the financial ratios prepare Balance sheet of Premier

India Ltd as on 31st March 2015.

Current ratio= 2.5; Liquidity ratio= 1.5; Net working Capital= 6,00,000; Stock turnover ratio=

5; Gross profit to sales =20%. Turnover ratio to net fixed assets (on cost of sales) =2; Average

debt collection period = 2.4 months; Fixed asset to net worth =0.8; Long term debt to capital

and Reserves =7:25.

1 of 2

R10 SET -4

||''''|||''|'''||''|

Code No: R21022

7. From the following prepare Trading, Profit and loss and Balance Sheet as on 31st March 2015.

Particulars Debit Credit

Capital 20000

Purchases 29000

Sales 55000

Carriage Inwards 5000

Wages outstanding 2000

Plant 20000

Depreciation on plant 4000

Rent received 1000

Salaries and wages 3000

Reserve for bad and doubtful debt 1000

Bad debts 2000

Interest 5000

Premises 20000

Interest paid 5000

Creditors 6000

Opening stock 25000

Loans 38000

Debtors 15000

Adjustment

Closing stock at the end: Rs 40,000

Depreciate building at the rate of 15% per annum.

8. A ltd is considering to purchase a new machine costing Rs 5,85,000. An additional investment

will be required for installation costing Rs 15,000 and for working capital Rs 1,00,000. The

machine has a working life of 5 years and salvage value will be Rs 1,00,000. The working

capital will be released after 5 years. The estimated cash inflows before depreciation and tax are

estimated as follows

Years Cash Inflows (Rupees)

1 1,00,000

2 1,80,000

3 2,50,000

4 2,00,000

5 1,50,000

You can assume straight line method for charging depreciation, cost of capital of 15% and

corporate tax rate of 50%. Should the company purchase the machine?

2 of 2

R10 SET -4

||''''|||''|'''||''|

Code No: PT21012


NETWORK ANALYSIS (Electronics and Communication Engineering)


Note: 1. Question Paper consists of two parts (Part-A and Part-B)

2. Answer ALL the question in Part-A

3. Answer any THREE Questions from Part-B

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PART –A

1 a) Define the ideal sources and draw their characteristics

b) Define the super mesh with diagram

c) Definition the Q and write its expression for series resonance

d) States the Milliman’s theorm

e) Write the basic equations for Inverse Transmission line parameters

f) Define and obtain the time constant R-C circuit

PART -B

2 a) Definition the various terms associated with periodic functions

b) A Wheatstone bridge consists of AB= 5 ohms, BC = 7ohms, CD = 6 ohms and

DA = 5 ohms. A 10V cell is connected between A and C. Find the current through

galvanometer connected between B and D.

3 a) A circuit consists of a resistance of 15 ohm, a capacitance of 300 µF, and an inductor

of 0.06 H all in series. If supply of 240 V, 50 Hz is applied to the ends of circuit .

Calculate (i) current in coil, (ii) the potential difference across each element, and (iii)

the frequency at which current would have unity power factor.

b) Describe the super node and super mesh with suitable example

4 a) Two identical coils A and B, each having 3000 turns, lie in parallel planes such that

70% of the lines of force produced by one link the other. A current of 5 A in coil A

produces a flux of 0.06 mWb. If the current in the coil A changes from +8 A to – 8 A

in 0.05 sec, what will be the magnitude of the emf induced in B? Also, calculate the

self-inductance of each coil.

b) An impedance coil having a resistance of 10 ohm and inductance of 12 mH is

connected in parallel with a capacitor; find the value of this capacitor if the circuit

undergoes resonance when a 50 V, 230 Hz source is applied. Also determine the line

current under resonance.

R13 RA

1 of 2

||''''|||''|'''||''|

Code No: PT21012

5 a) State and explain the compensation theorem

b) Determine the current through the 9-resistor for the following network using

superposition theorem below Figure 1.

6 Find the Y-parameters of the circuit shown in below Figure 2.

7 a) Obtain the Laplace transform of useful functions

b) In the network shown in below Figure 3, the switch is closed at t = 0. Find the values

of i1(t) and i2 (t), assuming zero initial currents through inductors.

1 of 2

R13 RA

2 of 2

||''''|||''|'''||''|

Code No: R21042


NETWORK ANALYSIS (Com. to ECE, EIE, ECC)


Answer any FIVE Questions All Questions carry Equal Marks

~~~~~~~~~~~~~~~~~~~~~~ 1 a) Explain the classification of Network elements and give suitable examples for each

element. [8]

b) Find the equivalent resistance for the circuit shown below across x – y.

[7]

2 a) Define and explain the following terms: i)Root mean square value and ii) Average Value

[7]

b) Find the average and effective values of Saw tooth wave form shown below:

[8]

3 a) Derive the necessary equations for converting star connected resistances to delta connected resistances.

[8]

b) In a series RL circuit the current and voltage are given as I = 4 cos (314t – 200) A, V = 10 cos (314 t + 100)V. Find the values of R and L.

[7]

4 a) Explain the properties of resonance for a series RLC circuit [7]

b) A coil having an inductance and resistance of 50 mH and 100 Ω is connected in series with a capacitor and a 100 V, 1K Hz Source. Obtain the value of capacitance that will cause the resonance in the circuit. Find the circuit current at resonance frequency.

1 of 2

[8]

SET - 1 R10

||''''|||''|'''||''|

Code No: R21042

5 a) State and explain compensation theorem [7]

b) Calculate the current in 4Ω resistor for the circuit shown below using Millman’s

theorem.

[8]

6

Obtain Z – Parameters and transmission parameters for the circuit shown below.

[15]

7 a) What are the merits and demerits of Laplace transform [8]

b) Given that current in the circuit at t = 0 is 5A. Obtain i(t) at t = 0+ for the figure

shown below:

[7]

8 a) Analyze m – derived low pass filter. [8]

b) Explain Band elimination filter [7]

2 of 2

SET - 1 R10

||''''|||''|'''||''|

Code No: R21042


NETWORK ANALYSIS

(Com. to ECE, EIE, ECC) Time: 3 hours Max. Marks: 75


~~~~~~~~~~~~~~~~~~~~~~

1 a) State and explain Kirchhoff’s voltage and current Law [8]

b) Determine the power supplied by the 10V battery for the network shown in below figure

[7]

2 a) Define the following terms i)Tree ii)Graph iii)node iv)Degree of a Node v)Link

[8]

b) A network is shown in the figure below: Draw its graph.

[7]

3

A circuit consists of a resistance of 15Ω, a capacitance of 300 µF and an inductor of 0.06H all in series. If the supply voltage is 240V,50 Hz applied to the ends of circuit. Calculate i) current in the coil ii) Potential difference across each element iii) the frequency at which the power factor is unity.

[15]

4 a) Explain the effect of resistance and inductance on the frequency response curve. [7]

b) Find the value of R1 such that the given circuit in figure is resonant. [8]

1 of 2

SET - 2 R10

||''''|||''|'''||''|

Code No: R21042

5 a) State and explain Norton’s theorem [7] b) Determine Norton’s equivalent circuit at terminals AB for the circuit shown in

figure below

[8]

6 a) Obtain open circuit parameters and loop equations of the network shown in figure below:

[8] b) Derive the relation between Z – parameters and ABCD parameters.

[7] 7

The following figure represents a parallel RLC circuit where R = 0.1Ω , L = 0.5 H and C =1 F. Capacitor has an initial voltage of 10V with polarity shown in figure. The switch K is closed at time t = 0. Obtain V(t)

[15]

8 a) What are Active and Passive filters? List the advantages of active filters over passive filters. [8]

b) A T- section low pass filter has series inductance 80 mH and shunt capacitance 0.022 µF. Determine the cut – off frequency and nominal design impedance. [7]

2 of 2

SET - 2 R10

||''''|||''|'''||''|

Code No: R21042





~~~~~~~~~~~~~~~~~~~~~~ 1 a) Define and explain the following terms:

i) Resistance ii) Inductance iii) Capacitance. [7]

b) Find the equivalent capacitance across x-y.

[8]

2 a) Explain the principle of Duality [7]

b) Draw the dual network for the circuit shown in figure below:

[8]

3 a) Explain the concept of complex Impedance and admittance [7]

b) Explain the response of series RLC circuit for sinusoidal excitation.

[8]

4 a) Define coefficient of coupling (K) and explain the dot rule for coupled circuits. [7]

b) In an ideal transformer, the mutual inductance is 10 H, number of primary and secondary turns are 50 and 200. Obtain the value of primary current to produce 0.5 Wb flux to link with the secondary coil.

[8]

1 of 2

SET - 3 R10

||''''|||''|'''||''|

Code No: R21042

5 a) State and explain superposition theorem [7]

b) Calculate the current across the 3 Ω resistor for the circuit shown below using super position theorem and also calculate the power across 3Ω resistor.

[8]

6 a) Obtain the short circuit parameters for the network shown below:

[8]

b) Derive the relation between Z – parameters and Y – parameters.

[7]

7 a) Obtain the transient response of RL series circuit having DC excitation. [7]

b) A series RL circuit having R = 25 Ω and L = 5H. A dc voltage of 100 V is applied at t = 0. Find the equations for current and voltage across R and L.

[8]

8 a) Compare m –derived and prototype filters. [7]

b) Design a m –derived low pass filter(T ) section having design resistance Ro = 500Ω, cut – off frequency fc = 1500 Hz and infinite attenuation frequency fα = 2000Hz.

[8]

2 of 2

SET - 3 R10

||''''|||''|'''||''|

Code No: R21042





~~~~~~~~~~~~~~~~~~~~~~

1 a) Explain the different types of sources in detail [8]

b) Find the source current for the circuit shown below:

[7]

2 a) Define form factor and peakl factor and also explain its significance. [7]

b) Determine the form factor for the wave form given below:

[8]

3 a) Explain the phase relations for the i) pure resistor ii) pure inductor iii) pure capacitor with phasor representations

[7]

b) Explain the response of parallel RLC circuit for sinusoidal excitation

[8]

4 a) Explain the difference between self inductance and mutual inductance [7]

b) From the following data, find the self and mutual inductances of the two windings 1 and 2 of ideal transformers operating in a linear zone N1 = 500 turns N2 = 750 turns I1 = 2A, Ø1 = 10mWb, Ø12 = 6mWb.

[8]

1 of 2

SET - 4 R10

||''''|||''|'''||''|

Code No: R21042

5 a) State and explain Norton’s theorem [7] b) Find the thevenin’s equivalent circuit for the network shown below:

[8] 6 a) Find Y –Parameters for the network shown below:

b) Derive the relation between Y –parameters and ABCD parameters.

[7] 7 a) Obtain transient response of RC circuit having DC excitation. [8] b) Calculate the time taken by a capacitor of 1 µF and in series with a 1MΩ resistance to

be changed up to 80 % of the final value. [7]

8 a) Explain about the classification of filters, along with the characteristics of each type of filter. [8]

b) Design a Low pass filter. [7]

2 of 2

SET - 4 R10

||''''|||''|'''||''|

Code No: R21043

II B. Tech I Semester Supplementary Examinations, June - 2015 PROBABILITY THEORY AND STOCHASTIC PROCESSES

(Electronics and Communications Engineering)




~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) Explain the term independent events and also write the properties of independent

events.

5

b) A binary communication channel carries data as one of the two types of

signals denoted by 0 and 1. Owing to noise a transmitted 0 is sometimes

received as 1 and a transmitted 1 is sometimes received as a 0. For a given

channel, assume a probability of 0.91 that a transmitted 0 is correctly received as a 0

and a probability of 0.94 that a transmitted 1 is received as a 1. Further assume a

probability of 0.4 of transmitting a 0. If a signal is sent, Determine

(i) Probability that a 1 was transmitted, given that a 1 was received

(ii) Probability that a 0 was transmitted, given that a 0 was received

10

2 a) Write the expressions for cdf and pdf of uniform and exponential random variables

and also sketch them.

5

b) Check whether the following function is a valid distribution function

GX(x) = 4[u(x-2a) - u(x-3a)]. Mention the properties used for justification.

4

c) Given k is a constant and X is a random variable with pdf

10

Find the value of c and P[1/2 < ¾]

6

3 a) Obtain the mean of Poisson random variable. 8

b) Define characteristic function of a random variable and write explain how moments

can be generated using it.

7

4 a) Define joint characteristic function and write its properties. 5

b) Two random variables X and Y have a joint probability density function

Check whether X and Y are statistically independent or not with supporting

expressions / values derived.

1 of 2

10

R10 SET - 1

||''''|||''|'''||''|

Code No: R21043

5 a) Define covariance of random variables X and Y and explain correlation coefficient.

5

b)

The density function of two random variables X and Y is

. Find the mean value of the function e–(X+Y)

.

10

6 a) State and prove any three properties of cross correlation function. 8

b) If a random process, is given, where A and B are

uncorrelated zero mean random variables having the variance σ2. Find autocorrelation

function of X(t).

7

7 a) Determine whether the following functions can be a valid power density function or

not? Support your claim with proper workout.

exp[-(ω-1)2]

3

b) State and prove Wiener-Khintchine relations

12

8 a) An LTI system is excited with a random process X(t). Obtain the expression for the

autocorrelation function of the response.

7

b) Write short notes on thermal noise. 8

2 of 2

R10 SET - 1

||''''|||''|'''||''|

Code No: R21043






~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) Write the axioms of probability. 5

b) Two boxes B1 and B2 contain 100 and 200 light bulbs respectively. B1 and B2 have

10 and 5 defective bulbs respectively.

i) Suppose a box is selected at random and one bulb is picked out. What is the

probability that it is defective?

ii) Suppose we test the bulb and it is found to be defective. What is the

probability, which it came from B1?

10

2 a) A random variable X has the pdf

8

b) Define a random variable. Classify random variables and explain.

7

3 a) Obtain the mean of Gaussian random variable. 8

b) A random variable X is uniformly distributed on the interval (-4, 12). Another

random variable is defined as Y = e-X/4

. Find E(Y).

7

4 a) Write the properties of joint distribution function. 5

b) Obtain the expression for pdf of sum of two statistically independent random

variables.

10

5 a) Prove that mean value of a weighted sum of random variables equals the weighted

sum of mean values.

8

b) Prove that any correlated Gaussian random variables are statistically independent

7

1 of 2

R10 SET - 2

||''''|||''|'''||''|

Code No: R21043

6 a) Check whether the random process X(t) = A cos(ωot +Θ) is WSS process or not, for

‘A’ and ωo being constant and Θ uniformly distributed between (0, π).

8

b) Explain the terms SSS process and Correlation ergodic process. 7



+ + 1

3

b) Derive the expression for cross power density spectrum.

12

8 a) Write short notes on thermal noise. 7

b) Derive the expression for noise figure of a cascaded two port network. 8

2 of 2

R10 SET - 2

||''''|||''|'''||''|

Code No: R21043






~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) With reference to mathematical modeling of experiments explain how is an

experiment defined mathematically.

5

b) An verification plan calls for verification of five chips and for either accepting each

chip, rejecting each chip, or submitting it for reverification, with probabilities of p1=

0.70, p2= 0.20, p3= 0.10 respectively. What is the probability that all five chips must

be reverified? What is the probability that none of the chips must be reverified?

6

c) Explain the terms continuous and discrete sample spaces

4

2 a) Write the expressions for cdf and pdf of Rayleigh and Poisson random variables and

also sketch them.

5

b)

Given the function , find the value of b so that

gX(x) is a valid probability density.

4

c) Write the properties of CDF and explain.

6

3 a) Obtain the mean of Uniformly distributed random variable. 8

b) Find the characteristic function of the random variable with pdf 1/b( e-(X-a)/b

). Also

find the first moment from it.

7

4 a) State and prove central limit theorem for equal distributions case. 10

b) Write the properties of joint density function.

5

5 a) The joint density function of two random variables X and Y is

Find the variances of X and Y.

10

b) Define joint characteristic function and write its properties.

5

1 of 2

R10 SET - 3

||''''|||''|'''||''|

Code No: R21043

6 a) Given that the autocorrelation function for a stationary ergodic process with no

periodic components is

Find the mean and variance of the process X(t).

b) Explain the terms WSS process and Mean ergodic process.



+ 1

3

b) Derive the expression for power density spectrum of a random process.

12

8 a) Write short notes on thermal noise. 8

b) Write short notes on average Noise figure. 7

2 of 2

R10 SET - 3

||''''|||''|'''||''|

Code No: R21043






~~~~~~~~~~~~~~~~~~~~~~~~~

1 a) Explain the terms sample space, outcome, event and mutually exclusive events with

an example.

7

b) State and prove Baye’s Theorem.

8

2 a) Define conditional density and write its properties. Also discuss different methods of

defining the conditioning event obtain the respective density functions.

10

b) Write the expressions for cdf and pdf of Gaussian and binomial random variables and

also sketch them.

5

3 a) Obtain the mean of Binomial random variable. 8

b) Define moment function of a random variable and write explain how moments can be

generated using it.

7

4 a) The joint pdf of random variables X and Y is given b

Check whether X and Y are correlated or not.

7

b) Joint density function of random variables X and Y are given by

Find constant b so that this is a valid joint density function. Also find

8

5 a) Two random variables X and Y have joint characteristic function

Show that X and Y are zero mean random variables and uncorrelated.

7

b) For the transformations where a, b, c, d are real

constants and X1 and X2 are random variables. Derive the expression for joint density

of Y1 and Y2 in terms of joint density of X1 and X2.

1 of 2

8

R10 SET - 4

||''''|||''|'''||''|

Code No: R21043

6 a) Prove that random process X(t)=A Cos(ωct+ ө) is a wide sense stationary process if it

is assumed that A, ωc are constants and Ө is uniformly distributed over interval

0≤ө≤2π.

8

b) Classify random processes and explain.

7



+ 3 + 3

3

b) Derive the relationship between cross correlation function and cross power spectrum.

12

8 a) Write short notes on Narrowband random process. 8

b) Write short notes on Effective Noise Temperature. 7

2 of 2

R10 SET - 4

||''''|||''|'''||''|

Code No: R21044


SIGNALS AND SYSTEMS (Com. to ECE, EIE, ECC, BME)




~~~~~~~~~~~~~~~~~~~~~~~~

1. a)Define and sketch the following signals

i) Signum Function

ii) Impulse function

iii) Unit step function

b) Define mean square error and derive the expression for evaluating mean square error

2. a) Find the Fourier series expansion of the half wave rectified sine wave shown below.

b) Find the even and odd components of the signal x(t)= sin t +cos t + cos t sint

3. a) Determine the fourier transform of the signal g(t)=A sinc2wt

b) Write a short notes of the following

i)Hilbert Transform ii)Modulation theorm

4. a) Find the impulse response of the system shown in figure 1 given below.Find the transfer

function.What would be its frequency response .Sketch its response .

b) List the properties of a LTI system and explain each property with an example.

1 of 2

SET - 1 R10

||''''|||''|'''||''|

Code No: R21044

5. a) If y(t)= x(t)* h(t) then show that x(t-t1) * h(t-t2) = y (t-t1-t2)

b) Derive an expression that relates energy spectral density and autocorrelation function.

6. a) The signal g(t)= 10 cos(20Пt)cos(200Пt) is sampled at the rate of 250 samples per

second. What is the Nyquist rate for g(t) as a low pass signal and determine the lowest

permissible sampling rate for this signal ?

b) State and explain sampling theorem for continuous signals?

7. a) Define Laplace transform and state the necessary conditions for its existence. List out its

advantages and disadvantages.

b) Determine the inverse Laplace transform of the following

i) ( )( )21

13

++

+

SSS

S ii)

( )( )521

12 +++

−

SSS

S

8. a) The z-transform of a particular discrete time signal x(n) is expressed as

( )1

1

5.01

5.01−

−

−

+=

Z

ZZX Determine the x(n) using the time shifting property1.

b) Explain the differentiation property of Z-transform?

2 of 2

SET - 1 R10

||''''|||''|'''||''|

Code No: R21044






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) )A rectangular function f(t) is defined by

( )

<<−

<<=

ππ

π

2,1

0,1

t

ttf

Approximate this function by a wave form ‘Sin t’ over the interval (0,2П)such that the mean

square error is minimum.

b) Explain how a function can be approximated by a set of orthogonal functions.

2. a) Consider the periodic square wave x(t) as shown in figure 1 given below.Determine the

complex exponential Fourier series of x(t).

b) State and prove the following fourier series properties.

i) Time Shift ii) Frequency shift

3. a) Determine the Fourier transform of the signal g(t)= 2 Sinc2wt

b) Find the Fourier Transform of Impulse function and Signum function

4. a) How can you verify a system is distortion less and explain the same with required details?

b) List out the properties of a LTI system and explain each property with a relevant example.

1 of 2

SET - 2 R10

||''''|||''|'''||''|

Code No: R21044

5. a) Compute the convolution sum y(n) to the following pair of sequences:

i) x(n)=y(n),h(n)= 2n u(-n) ii) x(n)=(1/2)

n u(n), ( )1

2

1)( −= nnh δ

b) State and prove convolution property of Fourier transforms.

6. a) Discuss sampling of continuous time signals.

b) Find the Nyquist rate and Nyquist interval for the signal

x(t)=1/2 cos (4000Пt)cos(1000Пt)

7. a) Discuss various properties of ROC’s for Laplace transform.

b) Determine the inverse Laplace transform of the following

8. a) Determine the inverse Z-transform of the following X (z) by the partial fraction expansion

method. 272

2)(

2 +−

+=

zz

zzX If the ROC’s are

i) |z|>3 ii) |z|<1/2 iii) 1/2<|z|<3

b) Explain the differentiation property of Z-transform.

2 of 2

SET - 2 R10

||''''|||''|'''||''|

Code No: R21044






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Check whether the following signals are orthogonal or not

X1(n)=ejk(П/8)n

and X2(n)= ejm(2П+/ П /8)n

b) A rectangular function f(t) is defined by

( )

<<−

<<=

ππ

π

2,1

0,1

t

ttf

Approximate this function by a wave form Sin t over the interval (0,2П) such that the mean

square error is minimum.

2. a) State all the properties of Fourier series.

b) Derive the relationship between trigonometric and exponential Fourier series coefficients.

3. a)Find the inverse Fourier transform of the following:

i) ( )( )2

1

jwawX

+= ii) ( )

jwawX

−=

1

b) Write a short notes of the following i)Hilbert Transform ii)Modulation theorem

4. a) Draw the ideal characteristics of Low pass, High pass, Band pass and Band stop filters.

b) Test the linearity, causality, time variance, stability of the system governed by the equation.

i)y(n)=ax(n)+b ii)y(n)=ncos[x(n)]

iii)y(n)=n[x(n)]2 iv)y(n)=x(n)+nx(n-1)

5. a) A system has an input x(t)= u(t) and ( )( )

.1

1

jwwH

+= Find energy spectral density of the

output.

b) Find the convolution of the following signals ( ) ( ) ( ) ( )., 2

21 tuetxtuetxtt == −

6. a) Discuss different sampling techniques.

b) Explain the effect of under sampling aliasing.

1 of 2

SET - 3 R10

||''''|||''|'''||''|

Code No: R21044

7. a) Define Laplace transform. Distinguish between Laplace transform and continuous time

Fourier transforms.

b) Find the output response y(t) of the RC low pass network as shown in the figure 1 given

below due to the input ( ) ( )tuettxRct /= convolution.

8. a) Determine the final value of the signal corresponding to the Z-transform

( )21 88.11

2−− −−

=zz

zzX

b) Explain different properties of ROC of Z transform.

2 of 2

SET - 3 R10

||''''|||''|'''||''|

Code No: R21044






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Derive the condition for the two signals ( ) ( )txtx 21 and to be orthogonal to each other.

b) Define mean square error and derive the expression for evaluating mean square error

2. a) Explain about Dirichlet’s conditions?

b) Explain the concept of complex Fourier spectrum with an example?

3. a) Find the Fourier transform of the triangular pulse

( )( )

>

>−=

Tt

TtTtAtx

;0

;/1

b) State and prove the following properties of Fourier transform:

i) Multiplication in time domain ii) Convolution in time domain

4. a) What is an LTI system? Explain its properties.

b) Find the impulse response of the system shown in the Figure 1 given below. Find the

transfer function. What would be its frequency response? Sketch the response.

5. a) Write short notes on cross correlation and its properties.

b) Find the power, rms value and sketch the PSD for the following signal.

X(t) = (A+sin100t)cos200t

1 of 2

SET - 4 R10

||''''|||''|'''||''|

Code No: R21044

6. a)Determine the Nyquist rate for a continuous time signal

x(t)= 6 cos 50П t+20 sin 300П t+10 cos100Пt

b) Explain the following terms:

i) Natural sampling ii) Importance of sampling theorem

7. a)State and prove initial and final value theorem wrt Laplace transform

b) Determine the Laplace transform of the following:

i) x(t)=sin(at) cos (bt)

ii) x(t)=Cos3 3t

iii) x(t)=t sinat

8. a) Determine the inverse Z-transform of the following X(z) by the partial fraction expansion

method.

( )272

22 +−

+=

zz

zzX

If the ROC’s are

i) |z|>3 ii) |z|<1/2 iii) 1/2<|z|<3

b) Explain different properties of ROC of Z transform

2 of 2

SET - 4 R10

code no: r21026 r10 set - 1 ii b. tech i semester ... ece-all.pdf... a 4 -pole, lap wound, d.c...

Documents