Maximum amount of thermal radiation is emitted at all wavelengths at any specified temperature by a/an __________ body.
Grey
Black
Opaque
White
Correct Answer :
A. Grey
Related Questions
'Cryogenics' is concerned with the generation & use of low temperature in the range of
0°K to 123°K
0°C to - 123°C
0°C to - 273°C
0°K to 273°K
Brass parts with high residual tensile stress at the surface are susceptible to season cracking (i.e. spontaneous cracking occuring on exposure to atmospheric corrosion), if its zinc percentage is more than
5
10
20
35
Which of the following is a boiler accessory
i.e., not a boiler mounting?
Blow off cock
Feed check valve
Feed water pump
Stop valve
With decrease in the grain size of a material, its creep resistance
Increases
Decreases
Remain constant
Either (A) or (B); depends on the material
Which of the following does not have a sharp melting point?
Thoria
Glass
Ice
Pig iron
Biological shield in a nuclear reactor is generally provided to protect against the
α-rays
β-rays
Gamma rays & neutrons
Electrons
__________ is the process used for setting up compressive stresses in the surface of a metal to improve its fatigue strength.
Lancing
Shot peening
Slugging
Spinning
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
Current employed in resistance welding ranges from __________ kVA/
.
1.2 to 2.5
4.5 to 6.2
7.5 to 8.5
10.5 to 15.5
Normalising does not __________ of a metal.
Improve machinability & tensile strength
Remove internal stresses
Refine the structure
Remove strains caused by cold working
Galvanic corrosion cannot be prevented by
Cathodic protection
Anodic protection
Usage of largest possible anodic area
Any one of these
In fluid flow, and heat and mass transfer, one encounters (i) kinematic velocity (μ), (ii) molecular diffusivity (θ) and thermal diffusivity (α). The units of these quantities are.
μ , α and θ all have units of m/s
μ , α and θ all have units of m2/s
α and θ have units of m2/s, while μ has unit of m/s
α and θ have units of m/s, while μ has unit of m2/s
In chemical dehumidification process
Wet bulb temperature increases
Dry bulb temperature remains constant
Dew point temperature increases
Dry bulb temperature increases
The lightest non-inflammable gas is
H2
He
Ar
O2
Air/fuel ratio on molar (volume) basis for combustion of methane with theoretical quantity of air with be
9.5 : 1
12.5 : 1
15.5 : 1
18.5 : 1
The highest stress that a material can withstand for a specified length of time without excessive deformation is called the __________ strength.
Creep
Endurance
Fatigue
None of these
__________ glass is used in the mercury in glass thermometer meant for measuring a temperature of 500°C.
Borosilicate
High silica
Supermax
Lead
Which of the following materials does not form adherent oxide film on surface?
Copper
Nickel
Aluminium
Gold & silver
When dry bulb temperature & wet bulb temperature of moist air is the same, it means that the
Partial pressure of water vapour is less than the total pressure
Humidity is < 100% & dew point temperature of air has not reached
Dew point temperature of air has not reached & air is not saturated fully
Air is fully saturated
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
A steam carrying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted will
Increase
Decrease
Remain unaffected
May increase or decrease; depends on the thickness of each layer
__________ is the most suitable lubricant for drawing mild steel wires?
Kerosene
Water
Sodium stearate
Lime water
Atomic __________ of an element is a whole number.
Weight
Number
Volume
Radius
The product out from a cupola is called
Wrought iron
Pig iron
Cast iron
None of these
Large scale fire on fuel gas line is normally extinguished by
Water
Steam
Foam
Nitrogen
For a first order chemical reaction, the concentration of the reactant decreases __________ with time.
Linearly
Exponentially
Logarithmically
Inversely
Temperature attained in soldering of metals is about __________ °C.
150-300
400-500
650-800
1000-1100
Runge-Kutta method is used to solve a/an
Ordinary differential equation of nth order
Simultaneous non-linear equation
Linear differential equation
None of these
Joule-Thomson co-efficient is the ratio of
Pressure change to temperature change occuring during adiabatic compression of a gas
Pressure change to temperature change occuring during adiabatic throttling of a gas
Temperature change to pressure change occuring during adiabatic compression of a gas
Temperature change to pressure change occuring during adiabatic throttling of a gas
The function of neutral flux used in the pyrometallurgy of metal extraction is to increase the __________ of the slag.
Fluidity
Basicity
Acidity
Viscosity