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  • Question

  • An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m2). The critical thickness of insulation will be


  • Options
  • A. 25 mm
  • B. 40 mm
  • C. 160 mm
  • D. 800 mm

  • Correct Answer
  • 25 mm 

    • More questions

    • 1. The mean effective pressure of a diesel engine having fixed compression ratio will __________ if cut off ratio decreases.

    • Options
    • A. increase
    • B. decrease
      • Discuss
    • 2. In a centrifugal casting method, the impurities are collected in the centre of the casting.

    • Options
    • A. Yes
    • B. No
      • Discuss
    • 3. The chimney draught varies with

    • Options
    • A. climatic conditions
    • B. temperature of furnace gases
    • C. height of chimney
    • D. all of these
      • Discuss
    • 4. Which of the following pump is sucessfully used for lifting water to the boilers?

    • Options
    • A. Centrifugal pump
    • B. Reciprocating pump
    • C. Jet pump
    • D. Air-lift pump
      • Discuss
    • 5. A thick pressure vessel is always used for the generation of steam, as it can withstand high pressures.

    • Options
    • A. True
    • B. False
      • Discuss
    • 6. First law of thermodynamics deals with

    • Options
    • A. conservation of heat
    • B. conservation of momentum
    • C. conservation of mass
    • D. conservation of energy
      • Discuss
    • 7. A small percentage of boron is added to steel in order to

    • Options
    • A. increase hardenability
    • B. reduce machinability
    • C. increase wear resistance
    • D. increase endurance strength
      • Discuss
    • 8. According to equation of continuity,

    • Options
    • A. w1a1 = w2a2
    • B. w1v1 = w2v2
    • C. a1v1 = a2v2
    • D. a1/v1 = a2/v2
      • Discuss
    • 9. In case ofsensible cooling of air, the coil efficiency is given by

    • Options
    • A. B.P.F. - 1
    • B. 1 - B.P.F.
    • C.
    • D. 1 + B.P.F.
      • Discuss
    • 10. The crown of the fire box is made hemispherical in order to resist intense heat in the fire box.

    • Options
    • A. True
    • B. False
      • Discuss

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