Magnetic permeability of iron is increased by its
Decarburising
Alloying with cobalt
Purification
Alternate heating & cooling
Correct Answer :
B. Alloying with cobalt
Related Questions
Blasting of tri-nitro-toluene (TNT) is done by mixing it with ammonium
Nitrate
Sulphate
Carbonate
Chloride
The pressure drop per unit length for laminar flow of fluid through a long pipe is proportional to (where, A = cross-sectional area of the pipe & D = Diameter of the pipe)
A
D
1/A
1/A2
Electrometallurgical methods of metal extraction is normally used for those metals
Whose oxide/ore is not reduced by carbon
Which fall in the category of alkali & alkaline earth metals
Which stands higher in the electrochemical series of the metal
All (A), (B) & (C)
Uniform ramming of sand in green sand moulding process leads to
Reduced chance of gas porosity
Greater dimensional stability of the casting
Uniform flow of molten metal into the mould cavity
Less sand expansion type of casting defect
Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type
Parallel flow with equal heat capacities
Counter flow with equal heat capacities
Counter flow with unequal heat capacities
Parallel flow with unequal heat capacities
Steel produced from phosphatic iron is __________ in nature.
Malleable
Ductile
Brittle
Tough
Silicon percentage in the silicon steel used for electrical appliances/equipments is
0.3-0.4
12-14
3-4
20-25
The critical pressure at which the latent heat of vaporisation of steam becomes zero is __________ Kg/cm2.
273.15
225.65
100.03
373.15
Which of the following phenomenon/ phenomena is/are diffusion controlled?
Dislocation climb
Cross-slip
Twinning
Recrystallisation
Thermit welding is categorised as the __________ welding.
Forge
Fusion
Resistance
Arc
At 100% relative humidity, the dew point temperature of moist air is
Less than the wet bulb temperature
More than the wet bulb temperature
Equal to the wet bulb temperature
Equal to the ambient temperature
Function of gear box is to
Reduce the speed
Obtain variable speed
Increase the speed
Produce high torque
A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place
The better insulation material should be put just next to pipe (i.e., inside)
The better insulating material should be put outside
Either of the insulating material could be put on either side
Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)
Which of the following is not an ore of copper?
Cryolite
Azurite
Chalcopyrite
Malachite
The units of the rate constant for a second order reaction are
__________ is used as a material of construction for the blade of power saw.
Wrought iron
Stainless steel
Mild steel
High speed steel
Glycerine is used as a coolant in cooling of some engines instead of water, because
Its higher boiling point (290°C) increases its heat carrying capacity
Comparatively less weight of coolant is required
Smaller radiator can be used
All a, b & c
If the head is doubled in & centrifugal pump, the power required will increase in the ratio of
23
23/2
25/2
21/3
Mho's scale of hardness, which consists of 10 standard minerals is used for the measurement of __________ hardness.
Scratch
Indentation
Dynamic
Rebound
A material being tested for endurance strength is subjected to the __________ load.
Impact
Completely reversed
Dynamic
Static & dynamic
A material is capable of resisting softening at high temperature, because of its property termed as
Hot temper
Hot hardness
Fatigue
Creep
At the point of boundary layer separation in fluid flow, the
Shear stress is maximum
Velocity gradient is flat
Density variation is maximum
Shear stress is zero
The __________ of a double acting reciprocating pump as compared to the single acting pump will be almost double.
Flow output
Head developed
Overall efficiency
Weight
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
Thermal conductivity of a material does not depend upon its
Mass
Volume
Surface area
All 'a', 'b' & 'c'
Enzymes belong to the category of
Proteins
Carbohydrates
Vitamins
Fats
Addition of __________ to steel does not help in improving its machinability.
Sulphur
Silicon
Lead
Phosphorous
Which of the following represents the correct time-temperature curve when a block of metal is heated above room temperature & then left to cool in the room following Newton's law of cooling in which the rate of temperature drop will go on decreasing with the passage of time.
Out of the following, the __________ pipe has the least corrosion resistance.
Mild steel
Copper
Cast iron
Wrought iron
Air standard Otto cycle is more efficient than the diesel cycle for the same
Heat addition & compression ratio
Heat addition & pressure
Compression ratio & pressure
Cylinder dimension & rpm