Description : Refractory metals are known for which of the following properties: w) lack of chemical reactivity x) low density y) high melting point z) high thermal conductivity
Last Answer : ANSWER: Y -- HIGH MELTING POINT
Description : Demonstrate how a bimetallic strip works in a thermostat.
Last Answer : In electric iron, when current passes through heating element, it becomes hot. The connected bimetallic strip also heats up. On getting hot, it bends and is disconnected from heating element so, circuit breaks and switches off the electric iron.
Description : With increase in temperature, the rate of leaching increases, because the (A) Diffusivity of solute increases (B) Viscosity of solvent decreases (C) Thermal conductivity of solute increases (D) None of these
Last Answer : (A) Diffusivity of solute increases
Description : Ice skating is possible and practical because of a unique property of water. Is it because: w) The coefficient of kinetic friction of steel on frozen water decreases with decreasing temperature x ... sublimes y) The melting point decreases with increasing pressure z) Ice is a good thermal insulator
Last Answer : ANSWER: Y -- THE MELTING POINT DECREASES WITH INCREASING PRESSURE
Description : Which of the following is universally employed as the low expansion metal in the bimetallic thermometer, which is an iron-nickel alloy containing 36% nickel and has very low co-efficient of expansion (1/20th of ordinary metals) ? (A) Invar (B) Constantan (C) Chromel (D) Alumel
Last Answer : (A) Invar
Description : On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because - (1) metals ... metals (3) metals are good conductors of heat (4) plastics have a higher thermal conductivity than metals
Last Answer : (3) metals are good conductors of heat Explanation: On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they ... from our fingers will flow to the metal cap much more quickly than to the plastic body.
Description : On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because : (1) metals ... metals (3) metals are good conductors of heat (4) plastics have a higher thermal conductivity than metals
Last Answer : metals are good conductors of heat
Description : Heat transfer rate per unit area is called (A) Thermal conductivity (B) Heat flux (C) Heat transfer co-efficient (D) Thermal diffusivity
Last Answer : (B) Heat flux
Description : Thermal diffusivity of a material (A) Has the unit m2 /sec (B) Is defined as K/ρ . Cp (C) Is the ratio of thermal conductivity to thermal capacity (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : In Fourier's law, the proportionality constant is called the (A) Heat transfer co-efficient (B) Thermal diffusivity (C) Thermal conductivity (D) Stefan-Boltzmann constant
Last Answer : (C) Thermal conductivity
Description : Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity) (A) 1/k (B) k (C) k2 (D) 1/k2
Last Answer : (B) k
Description : Which of the following building materials has the HIGHEST thermal conductivity? w) Southern pine wood x) common brick y) aluminum z) gypsum board or drywall
Last Answer : ANSWER: Y -- ALUMINUM
Description : What do the old type of furnace thermostats use for power?
Last Answer : The are usually wired in. We replaced our with a programmable just fine. You may need to get more “instruction” than the little book your new one comes with…That’s where the Internet comes in for rescue/help!
Description : A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of ... and thickness __________ metre. (A) 0.01 (B) 0.1 (C) 0.25 (D) 0.5
Last Answer : (B) 0.1
Description : One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is (A) 100 (B) 900 (C) 9000 (D) 10000
Last Answer : (D) 10000
Description : What does thermal diffusivity of metals signify.
Last Answer : Thermal diffusivity is associated with the speed of propagation of heat into solids during changes in temperature with time.
Description : Which °fine metals has the maximum thermal conductivity? (1) Iron (2) Aluminium (3) Silver (4) Copper
Last Answer : (3) Silver Explanation: Silver has the best thermal conductivity of 429 W/mK at RT (295K). It is followed by copper, gold and aluminium. Metals generally have very good electrical conductivity, that leads to high thermal conductivity.
Description : Which of the metals has the maximum thermal conductivity? (1) Iron (2) Aluminium (3) Silver (4) Copper
Last Answer : Silver
Description : Brass tubes are used in the manufacture of tubes of evaporators used in sugar and salt industries, mainly because of its (A) High co-efficient of thermal expansion (B) Low thermal conductivity (C) High corrosion resistance (D) All (A), (B) and (C)
Last Answer : (C) High corrosion resistance
Description : In the illustration, the component labeled D is a ______. EL-0033 A. fixed contact B. moving contact C. trip bar D. bimetallic strip
Last Answer : Answer: B
Description : A bimetallic strip is used to convert a temperature change - a) into mechanical displacement b) into electrical displacement c) into neither mechanical nor electrical displacement d) all of the above
Last Answer : A bimetallic strip is used to convert a temperature change - into mechanical displacement
Description : Which of the following physical properties is TRUE of most dense ceramic materials? w) high tensile strength x) good ductility y) high compressive strength z) high electrical conductivity
Last Answer : ANSWER: Y -- HIGH COMPRESSIVE STRENGTH
Description : The high expansion metal normally used in the bimetallic thermometer is __________ temperature measurement. (A) Brass for low (B) Nickel alloys for high (C) Both 'a' & 'b' (D) Aluminium for all
Last Answer : (C) Both 'a' & 'b'
Description : A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature ... drop (in °K) across the layer of material 'A' is (A) 125 (B) 133 (C) 150 (D) 160
Last Answer : (D) 160
Description : In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the (A) Rate of firing and emissivity of flame (B) Thermal conductivity of the charge & ... (C) Nature of process; whether batch, continuous or intermittent (D) All (A), (B) and (C)
Description : Which of the following variables affects the furnace capacity? (A) Temperature of flue gas (B) Thermal conductivity of stock (C) Thickness of heating stock (D) All (A), (B) and (C)
Description : Refractory bricks having high thermal conductivity is desirable, when it is to be used in the (A) L.D. converter (B) Blast furnace (C) Rotary kiln (D) Recuperator
Last Answer : (D) Recuperator
Description : What is a measure of the ability of a material to conduct heat? A. Specific heat capacity B. Coefficient of thermal expansion C. Coefficient of thermal conductivity D. Thermal conductivity
Last Answer : Thermal conductivity
Description : A wavelength is commonly measured in which one of the following units? w) radians x) angstroms y) electron volts z) seconds
Last Answer : ANSWER: X -- ANGSTROMS
Description : Close inspection of a failed metal part reveals artifacts on the fracture surface commonly referred to as "striations" or "beach marks". This indicates the component failed as a result of: w) Sudden overloading x) Cyclical loading y) Stress corrosion cracking z) None of the above
Last Answer : ANSWER: X -- CYCLICAL LOADING
Description : Units commonly used for entropy are: w) kilograms per degree Kelvin x) Joules per degree Kelvin y) Newtons per Coulomb z) ergs
Last Answer : ANSWER: X -- JOULES PER DEGREE KELVIN
Description : A COPPER strip is placed in one compartment of a voltaic cell and a wire connects this strip to a piece of metal in the other compartment through a voltmeter. If the voltmeter reads zero, the other piece of metal is: w) zinc x) mercury y) silver z) copper
Last Answer : ANSWER: Z -- COPPER
Description : Reactors in commercial nuclear power plants in the U.S. are often referred to as thermal reactors. A thermal reactor uses: w) fissionable plutonium-239 as fuel. x) a relatively low heat output. y) neutrons moderated to relatively low energies. z) liquid sodium as a coolant.
Last Answer : ANSWER: Y -- NEUTRONS MODERATED TO RELATIVELY LOW ENERGIES.
Description : The part of a nuclear power plant that prevents thermal pollution of lakes or rivers is the: w) reactor x) coolant/moderator y) cooling tower z) control rod
Last Answer : ANSWER: Y -- COOLING TOWER
Description : Energy stored in a body as thermal or internal energy consists of one of the following. Does it consist of: w) heat in the form of radiant energy x) molecular kinetic energy only y) molecular potential energy only z) both kinetic and potential energy
Last Answer : ANSWER: Z -- BOTH KINETIC AND POTENTIAL ENERGY
Description : According to the second law of thermodynamics, energy tends to become more and more unavailable for conversion from: w) thermal to kinetic energy x) kinetic to thermal energy y) thermal to mechanical energy z) mechanical to thermal energy
Last Answer : ANSWER: Y -- THERMAL TO MECHANICAL ENERGY
Description : Which of the following properties is generally found, in non-metals?' (1) Brittleness (2) Conductivity (3) Ductility (4) Malleability
Last Answer : (1) Brittleness Explanation: An important physical property of non metals is that they are brittle and hence cannot be beaten into sheets or drawn into wires. In other words, non-metals are non-malleable and non-ductile. Where stress is applied on nonmetals, they shatter into pieces.
Description : (3) reflection of light due to the presence of free electrons Explanation: Lustre (or luster) is the way light interacts with the surface of a crystal, rock, or mineral. The word ... conductivity, and high density. Typically they are malleable and ductile, deforming -under stress without cleaving.
Last Answer : Cloud is a colloidal dispersion of – (1) Air in a dispersion medium of water (2) Fog in a dispersion medium of water (3) Mist in a dispersion medium of air (4) Water drops in a dispersion medium of air
Description : Dittus-Boelter equation cannot be used for molten metals mainly due to its very low (A) Prandtl number (B) Grashoff number (C) Thermal conductivity (D) Viscosity
Last Answer : (A) Prandtl number
Description : Which of the following liquid metals has the highest thermal conductivity? (A) Molten sodium (B) Molten lead (C) Mercury (D) Molten potassium
Last Answer : (A) Molten sodium
Description : The ratio of thermal & electrical conductivity is same for all the metals at the same temperature; and at around room temperature, this ratio is proportional to(where, T = absolute temperature, °K) (A) T (B) 1/T (C) T2 (D) 1/T2
Last Answer : A) T
Description : Nitrous oxide, commonly called laughing gas, has been a matter of concern to environmentalists recently because: w) it is thought to cause cancer at low concentrations. x) it produces photochemical smog. y) it is a greenhouse gas. z) none of the above
Last Answer : ANSWER: Y -- IT IS A GREENHOUSE GAS.
Description : Which of the following commonly used condenser tube materials has the lowest thermal conductivity? (A) Admiralty brass (B) Stainless steel (C) Aluminium brass (D) Titanium
Last Answer : (B) Stainless steel
Description : What property of a metal describes the onset of plastic deformation in a tensile test? w) tensile strength x) elongation y) yield strength z) reduction in area
Last Answer : ANSWER: Y -- YIELD STRENGTH
Description : When a physical property such as charge exists in discrete "packets" rather than in continuous amounts, the property is said to be: w) discontinuous x) abrupt y) quantized z) noncontinuous
Last Answer : ANSWER: Y -- QUANTIZED
Description : The property by virtue of which metals can be beaten into thin sheets is known as: A. Density B. Malleability C. Conductivity D. Ductility
Last Answer : ANSWER: B
Description : Pick out the correct statement. (A) 1 kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F (B) In steady state heat conduction, the only property of the substance which determines the ... in the direction of temperature rise (D) In heat transfer by forced convection, Grashoff number is very important
Last Answer : (B) In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity
Description : ick out the undesirable property for a good refrigerant. (A) High thermal conductivity (B) Low freezing point (C) Large latent heat of vaporisation (D) High viscosity
Last Answer : (D) High viscosity
Description : Which of the following is an undesirable property of slag produced during the Pyrometallurgical method of metal extraction from its ore? (A) High fusibility & fluidity (B) High thermal conductivity (C) Low density (D) High chemical activity
Last Answer : B) High thermal conductivity
Description : An explorer is riding his camel in the desert. Up ahead he sees what appears to be a pool of water. He can tell if it is a real pool of water or a mirage by putting on his polarized sun ... not be able to discern a difference z) both are polarized so one will not be able to discern a difference
Last Answer : ANSWER: X -- REFLECTIONS FROM WATER ARE POLARIZED WHILE THE MIRAGE S NOT