CBSE NET Electronic-Science June-2013 Solved Paper II

  1. In intrinsic semiconductor

    1. The electron density is twice the whole density

    2. The electron density is thrice the whole density

    3. The electron density is square root of the whole density

    4. The electron density is same as the whole density

    Answer: d

  2. PN junction diode can be used as a/an

    1. Oscillator

    2. Amplifier

    3. Insulator

    4. Rectifier

    Answer: d

  3. Norton's equivalent form in any complex impedance circuit consists of

    1. An equivalent current source in parallel with an equivalent resistance.

    2. An equivalent voltage source in series with an equivalent resistance.

    3. An equivalent current source in parallel with equivalent impedance.

    4. An equivalent voltage source in series with equivalent impedance.

    Answer: c

  4. Zener diode is a

    1. Reverse biased diode

    2. Variable voltage source

    3. Constant current source

    4. Forward biased diode

    Answer: a

  5. Which of the following oscillator make use of both positive and negative feedbacks?

    1. Hartley oscillator

    2. Colpit's oscillator

    3. Phase shift oscillator

    4. Wein-Bridge oscillator

    Answer: d

  6. Superposition theorem can be applied only to circuits having

    1. Resistive elements

    2. Passive elements

    3. no-linear elements

    4. Linear bilateral elements

    Answer: d

  7. Identify the fastest analogue to digital converter

    1. Ramp conversion

    2. Parallel conversion

    3. Successive approximation

    4. Dual-slope integration

    Answer: b

  8. 1 K memory device contain

    1. 1064 memory cells

    2. 1024 memory cells

    3. 512 memory cells

    4. 640 memory cells

    Answer: b

  9. Which logic function has the output low only when both inputs are high?

    1. NOR

    2. OR

    3. AND

    4. NAND

    Answer: d

  10. In FM, when frequency deviation doubled, then

    1. Modulation Index is decreased

    2. Modulation Index is doubled

    3. Modulation Index halved

    4. No change occurs in modulation index values

    Answer: b

  11. Out of the followng memory types, one that is volatile is

    1. Magnetic disc

    2. Ferrite core

    3. Semiconductor ROM

    4. Semiconductor RAM

    Answer: d

  12. An SCR can be formed by using

    1. 2 npn transistors

    2. 2 pnp transistors

    3. 1 npn and 1 pnp transistor

    4. 2 pn diode

    Answer: c

  13. The pH of human blood is between

    1. 6.5 to 7

    2. 7.5 to 8

    3. 8 to 9

    4. 4.5 to 5

    Answer: b

  14. What is SIM?

    1. Select Interrupt Mask

    2. Sorting Interrupt Mask

    3. Set Interrupt Mask

    4. Start Instruction Mode

    Answer: c

  15. Quantization noise occurs in

    1. TDM

    2. PCM

    3. FDM

    4. WDM

    Answer: b

  16. Which antenna gets circularly polarized?

    1. Yagi-Uda

    2. Dipole

    3. Parabolic

    4. Helical

    Answer: d

  17. VSWR (Voltage Standing Wave Ratio) is always

    1. More than 1

    2. Less than 1

    3. 1

    4. 0.4

    Answer: a

  18. The ladder network used in D/A converter is

    1. Weighted resistance ladder

    2. R – R ladder

    3. R – 2R ladder

    4. R – C ladder

    Answer: c

  19. Latch is a

    1. T flip-flop

    2. Master-slave JK flip-flop

    3. D flip-flop

    4. JK flip-flop

    Answer: c

  20. In LED, light is emitted, because

    1. Diode emits light when gets heated.

    2. Recombination of charge carrier takes place.

    3. Light is made to reflect due to lens action.

    4. LED amplifies the light falling on it.

    Answer: b

    • Assertion (A): 8421 code is weighted code.
    • Reason (R): 8421 code is self-complementary.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: c

    • Assertion (A): A stack is a type of non-sequential access memory system.
    • Reason (R): Memory stacks help in keeping track of return addresses and saving data for subroutines.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

      1. Both A and R are true and R is the correct explanation of (A).

      2. Both A and R are true, but (R) is not correct explanationof (A).

      3. A is true, but R is false.

      4. A is false, but R is true.

      Answer: d

    • Assertion (A): TEM waves exist in a waveguide.
    • Reason (R): Phase velocity and wave impedance for TEM waves are independent of the frequency of the waves.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: d

    • Assertion (A): In FSK, a binary 1 usually produces a hgher carrier frequency than a binary 0.
    • Reason (R): FSK maintains a constant amplitude carrier.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: b

    • Assertion (A): An LTI discrete system represented by the difference equation y (n + 2) – 5y (n + 1) + 6y (n) = x (n) is unstable.
    • Reason (R): A system is unstable if the roots of the characteristic equation lie outside the unit circle.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: a

    • Assertion (A): Stimulated emission is the key to the operation of LASER.
    • Reason (R): An important property of LASER radiation is its coherence, under which is meant the correlation between the phases of oscillation at different positions in space and at various moments of time.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: a

    • Assertion (A): R − 2R ladder type D/A converter has a higher speed of conversion than a weighted resistance D/A converter.
    • Reason (R): R–2R ladder type converter uses a smaller number of components than the weighted resistance D/A converter.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: c

    • Assertion (A): UJT is used in relaxation oscillators.
    • Reason (R): UJT has negative resistance region in its characteristics.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: a

    • Assertion (A): The race hazard problem does not occur in combinational circuits.
    • Reason (R): The output of a combinational circuit depends upon present inputs only.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: a

    • Assertion (A): Digital communication needs some synchronisation signals.
    • Reason (R): ‘bit syn’ signal isrequired in time divisionmultiplexing to distinguishgroups of data.
    1. Both A and R are true and R is the correct explanation of (A).

    2. Both A and R are true, but (R) is not correct explanationof (A).

    3. A is true, but R is false.

    4. A is false, but R is true.

    Answer: b

  21. Consider the following logic families:

    1. MOS

    2. TTL

    3. RTL

    4. ECL

    The correct sequence of the logic families in the order of their increasing noise margin is

    1. 3, 4, 1, 2

    2. 3, 4, 2, 1

    3. 4, 3, 2, 1

    4. 4, 3, 1, 2

    Answer: b

  22. Which is the correct sequence in the generation of PCM?

    1. Sampling

    2. Converting to PAM

    3. Quantization

    4. Adding of supervisory signal

    5. Encoding

      1. 1, 2, 5, 3, 4

      2. 1, 5, 2, 3, 4

      3. 1, 2, 3, 5, 4

      4. 4, 5, 1, 2, 3

      Answer: c

  23. Consider the following logic families:

    1. MOS

    2. CMOS

    3. DTL

    4. TTL

    The correct sequence of power dissipation in increasing order is given by

    1. 2, 1, 3, 4

    2. 2, 1, 4, 3

    3. 1, 2, 3, 4

    4. 1, 2, 4, 3

    Answer: a

  24. The data can be transmitted by following means:

    1. Coaxial cables

    2. MMF

    3. SMF

    4. Twisted wire cable

    The correct sequence in the increasing order of Bandwidth is

    1. 2, 3, 1, 4

    2. 4, 1, 2, 3

    3. 4, 1, 3, 2

    4. 1, 4, 2, 3

    Answer: b

  25. Consider the following devices:

    1. BJT in CB mode

    2. BJT in CE mode

    3. JFET

    4. MOSFET

    The correct sequence of these devices in increasing order of their impedance is

    1. 2, 1, 3, 4

    2. 2, 1, 4, 3

    3. 1, 2, 3, 4

    4. 1, 2, 4, 3

    Answer: c

  26. In the following question Match List-I with List-II

    List-I List-II
    1. SCR

    2. Triac

    3. Chopper

    4. Cycloconverter

    1. dc drve control

    2. Induction motor control

    3. Unidirectional

    4. Bidirectional

    • A
    • B
    • C
    • D
      • 4
      • 3
      • 1
      • 2
      • 1
      • 2
      • 3
      • 4
      • 3
      • 4
      • 1
      • 2
      • 1
      • 4
      • 2
      • 3

    Answer: c

  27. In the following question Match List-I with List-II

    List-I List-II
    1. Varistor

    2. Varactor diode

    3. Gunn diode

    4. PIN diode

    1. nonlinear resistance

    2. Nonlinear reactance

    3. Negative resistance

    4. Controllable impedance type

    • A
    • B
    • C
    • D
      • 1
      • 2
      • 3
      • 4
      • 2
      • 3
      • 4
      • 1
      • 3
      • 4
      • 1
      • 2
      • 4
      • 1
      • 2
      • 3

    Answer: a

  28. In the following question Match List-I with List-II

    List-I List-II
    1. Klystron

    2. Reflex Klystron

    3. Magnetron

    4. Gunn diode

    1. Cross-field device

    2. Bunching

    3. Velocity modulation

    4. Negative resistance

    • A
    • B
    • C
    • D
      • 2
      • 3
      • 1
      • 4
      • 1
      • 2
      • 3
      • 4
      • 4
      • 1
      • 2
      • 3
      • 1
      • 2
      • 4
      • 3

    Answer: a

  29. In the following question Match List-I with List-II

    List-I List-II
    1. LED

    2. LASER

    3. Solar Cell

    4. Photo diode

    1. Stimulated emission

    2. Spontaneous emission

    3. Power generator

    4. Detector

    • A
    • B
    • C
    • D
      • 1
      • 2
      • 3
      • 4
      • 2
      • 1
      • 3
      • 4
      • 3
      • 4
      • 1
      • 2
      • 4
      • 1
      • 2
      • 3

    Answer: b

  30. In the following question Match List-I with List-II

    List-I List-II
    1. DAA

    2. LXI

    3. RST

    4. JMP

    1. Program control instruction

    2. Data movement instruction

    3. Interrupt instruction

    4. Arithmetic instruction

    • A
    • B
    • C
    • D
      • 1
      • 2
      • 3
      • 4
      • 4
      • 2
      • 3
      • 1
      • 3
      • 4
      • 1
      • 2
      • 2
      • 1
      • 3
      • 4

    Answer: b

  31. In the following question Match List-I with List-II

    List-I List-II
    1. 8031

    2. 7490

    3. 74155

    4. 74151

    1. Multiplexer

    2. Demultiplexer

    3. Microcontroller

    4. Decade counter

    • A
    • B
    • C
    • D
      • 3
      • 4
      • 2
      • 1
      • 1
      • 2
      • 3
      • 4
      • 2
      • 3
      • 4
      • 1
      • 3
      • 1
      • 2
      • 4

    Answer: a

  32. In the following question Match List-I with List-II

    List-I List-II
    1. Bourdon tube

    2. Strain gauge

    3. Thermistor

    4. LVDT

    1. Distance

    2. Temperature

    3. Pressure

    4. Stress

    • A
    • B
    • C
    • D
      • 1
      • 2
      • 3
      • 4
      • 3
      • 4
      • 2
      • 1
      • 2
      • 3
      • 4
      • 1
      • 1
      • 3
      • 2
      • 4

    Answer: b

  33. Match the two lists List-I and List-II

    List-I (Types of ADC) List-II (Characteristics)
    1. Parallel comparator (i.e.. Flash) type

    2. Successive approximation

    3. Dual slope

    4. Counter type

    1. integrating type

    2. Fastest converter

    3. Conversion time is independent of the amplitude of the analogue signal

    4. Uses DAC in feedback path

    • A
    • B
    • C
    • D
      • 2
      • 3
      • 1
      • 4
      • 1
      • 2
      • 4
      • 3
      • 4
      • 3
      • 2
      • 1
      • 4
      • 2
      • 3
      • 1

    Answer: a

  34. In the following question Match List-I with List-II

    List-I List-II
    1. Flip-Flop can be used as latch

    2. Flip-Flop can be used as delayed

    3. Flip-Flop does not have race problem

    4. Flip-flop can be used as shift registers

    1. D Flip-flop

    2. Master-Slave

    3. JK

    4. R-S

    • A
    • B
    • C
    • D
      • 4
      • 1
      • 2
      • 3
      • 2
      • 4
      • 1
      • 3
      • 1
      • 3
      • 2
      • 4
      • 3
      • 1
      • 4
      • 2

    Answer: a

Read the paragraph and answer the questions 46 to 50:

Microwave tubes are used as microwave amplifiers and oscillators. Three general type of microwaves tubes in which third type of tubes are useful. In this tube there is an interaction between an electron and an RF field is continuous. The Travellng Wave Tube (TWT) is the prime example of this interaction. It is an amplifier whose oscillator counterpart is called Backward Wave Oscillator (BWO). Another group of tube in which a magnetic field ensures a constant electron beam – RF field interaction and this is complimented by the cross-field amplifier (CFA). Multi-cavity Klystron is used as an amplifier of microwaves and it consists of buncher cavity and cache cavity. The Reflex Klystron is a low power and low efficiency microwave oscillator. Reflex Klystron oscillator has been replaced by various semiconductor oscillators.

  1. One of the following is unlikely to be used as pulsed device. It is the

    1. Multi-cavity Klystron

    2. BWO

    3. CFA

    4. TWT

    Answer: b

  2. One of the reason why vacuum tubes eventually fail at microwave frequencies is that their

    1. Noise figure increases

    2. Transit-time becomes too short

    3. Shunt capacitive reactance becomes too large

    4. Series inductive reactance become too small

    Answer: a

  3. The Multi-cavity Klystron

    1. Has a high repeller voltage to ensure a rapid transit time.

    2. Is not a good low-level amplifier because of noise.

    3. Is not suitable for pulsed operation.

    4. Needs a long transit time through the buncher cavity to ensure current modulation.

    Answer: b

  4. Indicate the false statement. Klystron amplifiers may use intermediate cavities to

    1. Increase the band width of the device

    2. Improve the power gain

    3. Increase the efficiency of the Klystron

    4. Prevent the oscillations that occur in two cavities Klystron

    Answer: d

  5. TWT is sometimes preferred to the multi-cavity Klystron amplifier because the former

    1. Is more efficient

    2. Has a greater band width

    3. Has a higher number of modes

    4. Produces a higher output power

    Answer: b