Electromagnetic radiations propagate in vacuum with a velocity of _______________ metre/second?

Related Mcqs:

1. Which of the following is generally considered as opaque surface towards radiations ?

   A. Gases
   B. Solids
   C. Liquids
   D. Both B. and C.

2. For a laminar flow of fluid in a circular tube, ‘h1’ is the convective heat transfer co-efficient at velocity ‘V1’. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is________________?

   A. 1.26 h1
   B. 0.794 h1
   C. 0.574 h1
   D. 1.741 h1

3. The range of electromagnetic spectrum important in heat transfer by radiation is ______________ microns?

   A. 0.38-0.78
   B. 0.5-50
   C. 100-1000
   D. 5-50

4. Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around _____________ metres/second?

   A. 1
   B. 10
   C. 20
   D. 30

5. In a single evaporator system, the steam economy ________________ by creating vacuum in the evaporator?

   A. Increases
   B. Decreases
   C. Remain constant
   D. May increase or decrease, depends on the vacuum

6. Vacuum is generally maintained in the vapour space of an evaporator mainly to__________________?

   A. Get economical temperature difference by using moderate pressure steam
   B. Facilitate forward feeding in multiple effect evaporation
   C. Concentrate heat sensitive materials
   D. Achieve very high concentration of the final product

7. Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be_________________?

   A. 0.35
   B. 0.45
   C. 0.55
   D. 0.85

8. The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is ________________?

   A. 2
   B. 1/2
   C. 4
   D. 1/4

9. In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to _____________ the velocity head?

   A. Twice
   B. Four times
   C. Square root of
   D. Square of

10. If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is_________________?

    A. 1
    B. 2
    C. 1/2
    D. 4