A semi-conductor is damaged & behaves like a conductor, on passing a strong electric current through it, because it heats up the crystals & breaks the covalent bonds resulting in _______________ electrons ?
(A) Lack of free
(B) Excess of
(C) Decrease in
(D) None of these
In a furnace with heating element temperature at 1700°C, the dominant mechanism of heat transfer will be__________________?
(A) Conduction
(B) Radiation
(C) Natural convection
(D) Forced convection
Pick out the wrong statement about coating/electroplating of metals ?
(A) Phosphate coating is used as an excellent base for paints & enamels
(B) Phosphate coating is less corrosion resistant than chromate coating
(C) The base metal to be electroplated is normally made the cathode of the electrolytic cell and coating metal is made the anode
(D) Calorising is the process of coating steel with chromium
Nusselt number/Biot number varies___________________?
(A) Inversely with thermal conductivity
(B) Directly with heat transfer co-efficient
(C) Directly with thermal conductivity
(D) Inversely with the dimension of the solid
Hooke’s law_______________________?
(A) Applies to elastic deformation
(B) Applies beyond limit of proportionality in stress-strain curve
(C) States that stress is inversely proportional to strain upto elastic limit
(D) None of these
In case of a, centrifugal pump, the ratio h1/h2 is termed as the _____________ efficiency (where, h1 = actual measured head & h2 = head imparted to the fluid by impeller)?
(A) Mechanical
(B) Overall
(C) Volumetric
(D) Impeller
Increase in temperature, in general results in the____________________?
(A) Decrease in the viscosities of both liquids & gases
(B) Increase in the viscosities of both liquids & gases
(C) Increase in the viscosity of liquids and decrease in that of gases
(D) Decrease in the viscosity of liquids and increase in that of gases
Which of the following fastening devices has its both ends threaded ?
(A) Bolt
(B) Stud
(C) Set screw
(D) Split nut
. The effect of friction on the flow of steam through a nozzle is to decrease the _______________ of steam?
(A) Wetness
(B) Mass flow rate
(C) Both A & B
(D) Neither A nor B
_________________ is not a heat treatment process ?
(A) Cyaniding
(B) Parkerizing
(C) Austempering
(D) Martempering