Nusselt number/Biot number varies
Inversely with thermal conductivity
Directly with heat transfer co-efficient
Directly with thermal conductivity
Inversely with the dimension of the solid
Correct Answer :
A. Inversely with thermal conductivity
Related Questions
Thermal efficiency of an internal combustion engine is around __________ percent.
8
35
65
80
Dielectric
Is an electrical insulating material
Of low resistivity is preferred
Should have high thermal conductivity
Need not defy the corrosive action of chemicals
With increase in impurities in metals, their corrosion resistances
Increase
Decrease
Remain same
May increase or decrease; depending on the type of metal
When the wet steam is throttled but still remains wet at the exit of the throttle valve, then its temperature & dryness fraction respectively
Decreases & increases
Increases & increases
Increases & decreases
Decreases & decreases
Which of the following low melting alloy containing bismuth and lead is used for electric fuse?
Wood's metal
Babbitt metal
Monel metal
Duralumin
Cassiterite is an ore of
Tin
Lead
Molybdenum
Chromium
The excess air required for the combustion of pulverised coal is of the order of about __________ percent.
5
15
30
45
Limestone addition in the blast furnace is done to flux __________ present in the raw materials.
SiO2
Al2O3
MnO2
P
The ratio of mass of a neutron to that of an electron is about 1839. What is the ratio of the mass of a proton to that of an electron?
159
1837
2537
10000
The most abundant metal present in the earth's crust is;
Iron
Copper
Titanium
Aluminium
Use of water as a manometric liquid suffers from the disadvantage of its
Low vapour pressure
Corrosive nature
High vapour pressure
High boiling point
Annealing of white cast iron produces __________ iron.
Grey
Nodular
Malleable
Spheroidal
A common disinfectant used in village wells for disinfection of water is
Free chlorine
Bromine
Iodine
Potassium permanganate
__________ joint is mostly used for joining pipes carrying water at low pressure.
Nipple
Socket
Union
Bell and spigot
Magnetic permeability of iron is increased by its
Decarburising
Alloying with cobalt
Purification
Alternate heating & cooling
With increase in temperature, the surface tension of water
Increases
Decreases
Remain constant
Increases linearly
Non-ferrous alloys used for making cutting tools need not have high
Abrasion resistance
Toughness
Red hardness
Cutting speed
The elastic strain in copper is due to the
Motion of dislocations
Stretching of atomic bonds
Breakage of atomic bonds
None of the above
Viscoelastic behaviour is observed in __________ materials.
Non-crystalline organic polymeric
Ceramic
All crystalline
All amorphous
Blow off cock is provided in steam boiler to
Guard the boiler in case of abnormal rise in steam pressure
Drain out water and sludge during its repair
Regulate the supply of water in boiler
Put out the fire in the furnace when the water level in the boiler falls to unsafe limit
Resilience of a bolt can be increased by increasing its
Length
Shank diameter
Head diameter
None of these
Out of the following, the best material capable of withstanding shock & vibration without the danger of cracking is
Malleable iron
Grey cast iron
Chilled cast iron
White cast iron
Capacity & power requirement for an air compressor working at high altitude compared to sealevel will be
More
Less
Same
Either more or less; depends on the climatic conditions
Ganister contains maximum percentage of
FeO
SiO2
MgO
MnO2
Methyl orange indicator turns
Orange yellow in alkaline medium
Orange yellow in acidic medium
Colourless in acidic medium
Colourless in basic medium
Fibrous fracture is normally encountered in the __________ materials.
Hard
Elastic
Ductile
Brittle
When the wavelength of incident X-rays increases, the angle of diffraction
Decreases
Increases
Remain constant
Shows no systematic variation
Electrochemical corrosion can occur, only if __________ is present in contact with metal.
Air
Oxygen
Liquid medium
Gaseous medium
Cold cracking in the heat affected zone of a high strength steel weld can take place because of the
Retained austenite
Martensite formation
Relatively high sulphur content in the base metal
Sufficient hydrogen present in the welding arc
Pick out the wrong statement.
Geothermal energy is a non-conventional source of energy
Mass is converted into energy in both nuclear fission & fusion reaction
Inhalation of mercury vapour is not harmful for human beings
Inhalation of arsenic causes cancer