EMTL BITS

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                                                                   JNTUH BITS

                                           SECTION-I:   Multiple choice questions

Note:Don't think that these bots only will be repeated in mid exam.First through the last 4 units concepts well then solve the bits.These bits to cross check your knowledge

 1. For normal incidence of the wave on perfect conductor       [ b]

a) Surface current doesn’t exist b) surface exists  

c) conducting current exiasts d) free charge exists on the surface

2. A standing wave [ d]

a) Progresses with less than light velocity b) progresses with more than light velocity

c) progresses with equal to light velocity d) does not progress.

3. The range of reflection coefficient is [ c]

a) 0 to 1 b) 0 to infinity c) -1 to 1 d) 1 to infinity

4. Electric and magnetic fields which are parallel [d ]

a)Constitute power flow b) constitute infinite power flow

c)constitute unit magnitude power flow d) no power flow.

5. The propagation velocity of TE waves [ a]

a)Depends on frequency b) independent of frequency

c) depends on square of frequency d) varies inversely with frequency.

6. As per the boundary condition, [b ]

a)The normal component of E is continuous across the boundary.

b)The tangential component of E is continuous across the boundary.

c)The tangential component of D is continuous across the boundary.

d)The normal component of H is continuous across the boundary

7. The magnetic field at the surface of a good conductor is 2A/m. The frequency of the field is 600 MHz. The surface r.m.s current density is [c ]

a)0.5 A/m b)0.5 A/m2 c)2 A/m d)2 A/m2

8. If the reflection coefficient is -1/2 then the swr is [ d]

a)Zero b) one c)1/3 d) 3

9. The wave impedance over the cross section of wave guide [d ]

a) Increases with frequency b) decreases with frequency

c) increases exponentially d) constant

10. Hysteresis and eddy current losses in loading coils leads to [c ]

a) Increase in L b) Decrease in L c) Increase in R d) decrease in R

1 1) Which of these is not a correct form of the wave Ex = cos(ωt —βz)? [b ]

(a) Ex = cos(βz-ωt) (b) Ex = cos(ωt —βz-Π/2) (c) Ex = Re[ej(ωt —βz)] (d) Ex = cos(2Πt/T-2Πz/λ)

12) What is the major factor for determining whether a medium is free space, lossless dielectric, lossy dielectric, or good conductor? [ c]

(a) Attenuation constant (b) Constitutive parameters (σ,μ,ε)

(c) Loss tangent (d) Reflection coefficient

13) In a certain medium, E = 10 cos (108t — 3y) ax V/m. What type of medium is it? [ c]

(a) Free space (b) Perfect dielectric (c) Lossless dielectric (d) Perfect conductor

14) For any dielectric material ( σ/ωε) value is [a ]

a)<<1 b)>>1 c)=1 d)zero

15) Given that H = 0.5 e-0.1xsin (106t- 2x) ay A/m, which of these statements are incorrect? [ b]

(a) α = 0.1 Np/m (b)β = - 2 rad/m

(c) ω= 106rad/s (d) The wave is polarized in the z-direction.

16) Which of the following statements is not true of waves in general? [ a]

(a) It may be a function of time only. (b) It may be sinusoidal or cosinusoidal.

(c) It must be a function of time and space. (d) For practical reasons, it must be finite in extent.

17) For a lossy transmission line, the characteristic impedance does not depend on [ b]

(a) The operating frequency of the line (b) The length of the line

(c) The load terminating the line (d) The conductivity of the conductors

18) Which of the following statements are not true of the line parameters R, L, G, and C? [c ]

(a) R and L are series elements. (b) G and C are shunt elements.

(c)G = 1/R (d) LC = με and RG = σε.

19) A lossless transmission line of length 50 cm with L = 10 μH/m, C = 40 pF/m is operated

at 30 MHz. Its electrical length is [c ]

(a) 20λ (b) 0.2λ (c) 108° (d) 40Π

20) Ex = cos(ωt +βz) represents a wave travelling in the __________________ [d ]

(a)-ve x-direction (b)+ve x-direction (c)+ve z-direction (d)-ve z-direction

21. An electromagnetic wave is to pass through an interface separating two media having dielectric constants ε₁ and ε₂ respectively. If ε₁ = 4ε₂ , the wave will be totally reflected if angle of incidence is [b ]

( a ) 0⁰ ( b ) 30⁰ ( c ) 45⁰ ( d ) 60⁰

22. The Snell’s law of refraction

23. The instantaneous rate of energy flow per unit area at a point is [a ]

( a ) E x H ( b) ( c ) B • ∇D • ∇( d ) ) (2 EHx∇∇

24. When electromagnetic waves are reflected at an angle from a wall, their wavelength along the wall is

[ c]

( a ) shortened because of the Doppler effect ( b) the same as in free space

( c ) greater than in the actual direction of propagation

( d ) same as the wavelength perpendicular to the wall

25. At the cut-off wave length, the wave between the walls of parallel plane guide [d ]

( a ) is travel almost parallel to the axis of the guide

( b ) is travel perpendicular to the axis of the guide

( c ) is travel in zig-zag path ( d ) has no wave motion

26. If the time dependence of voltage is given as e^-jwt, then V_oe^-γz will represent [ b]

( a ) forward travelling wave (b ) backward travelling wave (c ) standing wave (d ) refracted wave

27. A lossless line of length 500m has L=10μH/m and C=0.1pF/m at 1 MHz. The electrical length of the line is

[ c]

( a ) 360⁰ ( b ) 270⁰ ( c ) 180⁰ ( d ) 90⁰

28. For an open circuited line which is not true [b ]

( a ) Zin = -jZo cotβl ( b ) ( c ) 1 −= Γ l 1 = Γ l ( d ) S = ∞

29. Short-circuited stubs are preferred to open-circuited stubs because the latter are [c ]

( a ) more difficult to make and connect

( b ) made of a transmission line with a different characteristic impedance

( c ) liable to radiate ( d ) incapable of giving a full range of reactances

30. For transmission-line load matching over a range of frequencies, it is best to use a [c ]

(a) balun (b) broadband directional coupler (c) double stub (d) single stub of adjustable position

SECTION-II:   Fill in the blanks

1. The frequency at which the wave motion ceases is called  Cutoff frequency.

2. A Lumped load line behaves as a  Low pass filter

3. By inserting inductance in series with the line to increase the inductance is called

 Loading.

4. One neper is =  8.68 dB.

5. A short circuited λ/4 line can be used a  Insulator

6. The range of UHF is 300 MHz to 3 Ghz

7. The loading practice is generally restricted to  Cables only.

8. When a transmission line is shorted, the first voltage minimum occurs at Load

9. The center of smith chart represents  Matched load impedance.

10. Attenuation factor of TEM wave is proportional to  Square root. of frequency.

11.The relation between E and H in any medium is ____________

12) The value of intrinsic impedance of free space is 377Ω

13) In a perfect dielectric medium attenuation constant is  Zero

14) The loss tangent value for a good conductor is  ( σ/ωε)>>1

15) A wave propagating in a conducting medium attenuation constant and phase constant values are_____________

16) The conductivity of silver is 3x106 mho/m.If the skin depth is 1mm,find the frequency?   84.43kHz

17) Write the expression for reflection coefficient of a perfect dielectic surface when the wave incident normal to the boundary.

 TR =(η2-η1)/(η2+η1)

18) The Poynting vector physically denotes the  power density leaving or entering  a given volume in a time-varying field

19) Brewster angle θB when the wave is parallally polarized is

20) Critical angle θc for the total internal reflection is

21. An electromagnetic wave is incident at air-conductor interface. If impedance of the conductor is 120π, the ratio of transmitted and incident electric fields is 2

22. The critical angle for a wave propagating from Teflon ( εr=4) into free space is 30˚

23. The orientation of the electric field with respect to the plane of incidence determines Polarization

of a wave at the interface between two different regions.

24. When the free-space wavelength of a signal equals the cutoff wavelength of the guide, the phase velocity of the signal becomes infinite

25. The wave impedances for waves between parallel planes are functions of frequency

26. A line is of a length ‘l’ has characteristic impedance ‘Zo’. The line is cut into half. The value of characteristic impedance becomes Zo

27. Impedance inversion may be obtained with Quarter  wave line

28. The velocity factor of a transmission line depends on the  dielectric constant of the material used

29. In a transmission line, the attenuation is given as 0.3dB/km. After 10km the power will be  0.5 of  input power

30. In electromagnetic waves, polarization is due to the  transverse  nature of the waves

                                                                                                                       

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STLD BITS

                                    JNTUH SECOND BITS

                                                       STLD

Note: 1.Don’t think that these bits only will be repeted in second mid.go through the concepts of last four units thoroughly then solve bits .these bits to cross check your knowledge

 1.The Programmable Array Logic consists of  [ d]

a) fixed OR and AND gates b) Programmable OR , fixed AND gates

c) Programmable OR and AND gates d) Programmable AND , fixed OR gates

2. A ring counter is useful in generating————- . [c ]

a) Frequency scaling b ) Pseud or and on pattern generation

c) Timing signals d ) Refresh address of DRAM

3. An ASM chart can be [ a]

a) converted to a state diagram & table and implemented as a Flip-Flop

b) converted into a state table

c) converted into astate diagram

d) implemented using gates & flip – flops

4. Four RAM chips of 16×4 size have their busses connected together. This system will be of size[c ]

a) 16×4 b) 256×1 c) 16×16 d) 32×8

5. The parameters of a threshold element are [ a]

a) weights assigned to input variable s and T b) output variables

c) weights assigned to input variables d) value of T

6. The table containing present state of output, next state of the output and the inputs is called[a ]

( a) Excitationtable ( b ) State table ( c ) Transition table e ( d ) Truth table

7. A finite state machine [a]

(a) same as clocked sequential circuits

(b) Neither Electrical motors nor clocked sequential circuits

(c) consists of electrical motors

(d) Electrical motors and clocked sequential circuits

8. The address bus with a ROM of size 1024*8 bits is [ b]

a)8 bits b) 10 bits c) 12 bits d) 16 bits

9. Which of the following flip flop is used as a latch – [b ]

a) JK flip flop b) D flip flop c)Master Slave flip d) T flip flop

10. Master slave configuration is used in flip flop to [c ]

a) Increase its clocking b) reduce power dissipation

c) Eliminate race around condition d) improve its reliability

 11.The ROM programmed during manufacturing process itself is called [ a]

a)MROM (b) PROM (c) EPROM (d) EEPROM

12. A memory in which the contents get erased when power failure occurs is [ d]

a)EAROM (b) PROM (c) ROM (d) RAM

13. A single literal term in SOP expression [ b]

a)Requires an inverter for PLA implementation

b)Requires an AND gate for PLA implementation

c)Doesn’t requires an AND gate for PLA implementation

d) Doesn’t requires an inverter for PLA implementation

14. When an inverter is placed between the inputs of an S – R flip – flop, the resulting flip – flop is a [ d]

a)J - K flip - flop (b) Master – slave flip - flop c)T flip - flop (d) D flip - flop

15. Flip – flops can be used to make [c ]

a)Latches (b) Bounce – elimination switches c) Registers (d) All of the above

16. The output of a clocked sequential circuit is independent of the input. The circuit can be represented by [b ]

a)Mealy model (b) Moore model

c)Either Mealy or Moore model (d) Neither Mealy or Moore model

17. For designing a finite state machine k – maps can be used for minimizing the

[ d]

a)Excitation expressions of flip - flops (b) Number of flip – flops

c)Output logic expressions (d) Excitation and output logic expressions

18. While constructing a state diagram of sequential circuit from the set of given statements [b ]

a)A minimum number of states must only be used b)Redundant states may be used

c) Redundant states must be avoided d)None of the above

19. An ASM chart consists of [ d]

a)Only state boxes (b) only decision boxes c)Only decision and conditional output boxes (d) All the above.

20. Moore type outputs are [a ]

a)Independent of the inputs b)Dependent only on the inputs

c)Dependent on present state and inputs d)Any one of the above

21. An n-stage ripple counter can count up to [b ]

(a) 2n (b) 2n-1 (c) n (d) 2n-1

22. A mod-13 counter must have [ c]

(a) 13 flip flops (b) 3 flip flops (c) 4 flip flops (d) synchronous clocking

23. In programmable logic array [ c]

(a) AND –array is fixed &OR- array is programmable

(b) AND-array is programmable & OR-array is fixed

(c) both AND &OR array are programmable

(d) both AND &OR array are fixed

24. Total no.of programmable fuses in ‘n’ input ‘m’ output PROM is [ c]

(a) n (b) nXm (c) 2nXm (d) 2mXn

25. A decision box in an ASM chart [ c]

(a) does not have exit paths (b) have only one exit path

(c) has two exit paths (d) has one entry and has one exit path

26. The functional difference between an SR flip-flop and J-K flip-flop is that [ c]

(a) J-K flip-flop is faster (b) J-K flip-flop has feedback

(c) J-K flip-flop accepts both inputs 1 (d) J-K flip-flop does not require clock

27. An Asynchronous counter differs from synchronous counter in [b ]

(a) Mod number (b) Method of clocking

(c) the type of flip-flops used (d) the numberof states in a sequence

28. To serially shift a byte of data in to shift register there must be [c ]

(a)1 clock pulse (b)one load pulse (c)eight clock pulses d)one clock pulse in each 1 in the data

29. Programming a PLD device means [b ]

(a) writing software program (b) blowing electronic fuses

(c) writing assembly language program (d) writing C program

30. When power supply of ROM is switched off, its contents [ c]

(a) becomes zero (b) becomes all ones (c) remains same (d) are unpredictable

  

Section -2:Fill in the blanks

1.A PLA consists of  AND, OR and invert / non invert matrix

2. A ROM has 32K×8 organization. Its capacity in bits is  256 Kbits

3. The number of outputs of a threshold element is  1

4. A shift register using flip flop is called  Static shift register  

5. The minimum number of flip flops required for a mod-12 ripple counter is  4

6. A Johnson counter is also called as inverse feedback amplifier

7. If the outputs of two states are different after P-state transitions they are said to be

 P- Distinguishable

8.  Unspecified outputs provide additional flexibility on state reduction.

9. The Programmable Array Logic consists of  Programmable AND, fixed OR gates

10. The Moore type of output are represented inside the  State box in an ASM chart

11.In a positive unite function all the variables are only in  Un complemented form.

12.  Non threshold functions cannot be realized using a single threshold gate.

13. Master – slave configuration is used in J-K flip – flops to eliminate  Race around condition

14. A  Basic ring counter requires no decoding circuitry.

15. The process of assigning the states of a physical device to the states of a sequential machine is

known as  State assignment

16. The merger table method of state reduction is also called pull unger method or implication chart method.

17. A table which consists of the states of a minimal state machine is called a minimal cover table

18. The data processing path is commonly referred to as the data paths.

19.  Moore type of outputs are referred to as unconditional outputs.

20. A path through an ASM block from entry to exit is referred to as a  path

21. The sequential circuit is a combination of  combinational circuit and memory elements.

22. The characteristic equation of J-K flip flop is  JQ^I+K^IQ

23. If the binary word 1101 is entered serially into the 4-bit serial in parallel out shift register (initially clear), the Q outputs after two clock pulses are  0100

24. A combinational PLD with programmable AND array and programmable OR array is called as

 PLA

25. Next state variables in asynchronous sequential circuits are called  excitation variables.

26. A counter that triggers all the flip-flops together is called  synchronous counter.

27. In synchronous circuit output depends only on the present state of flip-flop is called

 Moore machine

 28. The full form of PROM is  programmable read only memory.

29.  State diagram is a pictorial representation of behavior of a sequential circuit.

30. A Jhonson counter uses D flip flops.

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ECA 5,6,7,8 UNITS BITS

NOTE: Don't think that these bits only will be repeated in second mid.Prepare all units thoroughly and just go through these   bits to cross check your knowledge.

                                             ECA

                                                      JNTUH OBJECTIVE EXAM

                                         UNIT-5: Feedback amplifiers

                                  SECTION-I:   Multiple choice questions

1.  Negative feedback in amplifier             [   b  ]

(a) Improves SNR at the input (b) improves SNR at the output  (c) Increases distortion (d) None of the above

2.  The gain of an amplifier with feedback is ______. [            a          ]

(a) A/1+Aβ (b) β/1+βa (c) β/1-βa (d) A/1-Aβ

3.  In voltage shunt feedback, the input impedance [   b   ]

a. increases b. decreases

c. depends on dc voltage applied d. depends on frequency of operation

4.  Which of the following combination can be used as a buffer_____ [  c ]

a. CE b. CB c. CC d. All

    Section-II:  Fill in the blanks

1.     The Trans conductance amplifier is also called as  Series – Series amplifier (or) Current – Series amplifier

2.     In an ideal voltage amplifier, the values of Ri & R0 are  ∞, 0

 3. The ratio of input impedance with feedback to without feedback is  1+Aβ

                                         

  

                                                   UNIT-6: Oscillators

                                     SECTION-I : Choose the correct answers

 1.An oscillator of LC type having a split capacitor in the tank circuit is [b ]

a. Hartley b. Colpitts c. Tuned d. Wein Bridge

2.  In a Crystal oscillator the frequency is very stable due to ___________ of the crystal [c ]

a. rigidity b. high Q c. vibration d. none

3.  For generating a sinusoidal wave of 1KHz frequency, the most suitable oscillator is ____ [ c]

(a) Hartley (b) Colpitts (c) Wien bridge (d) None of the above

4.  The frequency stability of LC oscillator is _______ than RC oscillators. [ a]

(a) less (b) more (c) either a or b (d) None of the above

5.  An important limitation of a crystal oscillator is ________. [ a]

(a) its low output (b) its high Q (c) less availability of quartz crystal (d) its high output

   SECTION-II: Fill in the blanks

1.      Non sinusoidal oscillators are also called  Multivibrators.

2.      The oscillator which uses inductive feedback is Hartley

     3.The oscillator that uses tapped capacitors in the tuned circuit Armstrong Oscillator.

    4. Electronic oscillations in which amplitude doesn’t change with time are called _

 Sustained or Undamped oscillations

   5 An oscillator using LC tuned circuit has L= 58.6μH & C=300pF, then the frequency of oscillations will be 1200 kHz

   6. In a RC phase shift oscillator, each RC section provides a phase shift of  60˚

                                             UNIT-7: Large signal amplifiers

                                     SECTION-I : Choose the correct answers

1.  With transformer connection to load the maximum efficiency of the class A amplifier will go up to a maximum of [c ]

a. 78.5% b.25% c.50% d.66%

2.  The units of derating factor in power amplifier is [b ]

a. Volts/oC b. Watts/ oC c. Watts/ Cm2 d. None

3.  In ____ power amplifier, the output signal varies for a full 3600 of the cycle. [a ]

(a)Class A (b) Class B (c) Class AB (d) None of the above

4.  Maximum theoretical efficiency of Class B push pull amplifier is ___. [d ]

(a)25.5% (b) 50% (c) 75% (d) 78.5%

   SECTION-II: Fill in the blanks

1.      Thermal resistance of the heat sink will be typically  3⁰ C/W

2.      If output power=20W and the input dc power=60W,then the efficiency of power amplifier is    33.3%

      3. In Class B power amplifier, Q-point is set  near cutoff

      4. The input transformer in push-pull power amplifier is  Step-up

     5. The output transformer in push pull power amplifier is Step down

                                        UNIT-8: Tuned amplifiers

                       SECTION-I : Choose the correct answers

1.  The purpose of resonant circuits in tuned circuits is [d ]

a. TO provide properly matching load impedence b. To reset unwanted harmonics

c. To couple power to load d. All of the above

2.  To reduce further harmonic distortion in large signal tuned amplifiers_______- is used [c ]

a. feedback configuration b. transformer coupling

c. Push Pull configuration d. all of the can be used

3.  In tuned amplifiers, harmonic distortion is ____________. [c ]

(a) Infinite (b) more (c) less (d) None

4.  Double tuned amplifier provides ____ bandwidth than single tuned amplifiers. [ a]

(a)larger (b) smaller (c) negligible (d)constant

5.  Tuned amplifiers can be used in _____. [c ]

(a)Radar (b) IF amplifiers (c) both a and b (d) None

SECTION-II: Fill in the blanks

1. Small signal tuned amplifiers are operated in  Class A mode.

 2. Parallel tuned circuit is also known as  Anti resonant circuit

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