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4

With increase in temperature, the electrical conductivity of a __________ decreases.

A. Semi-conductor

B. Metal or alloy

C. Dielectric

D. None of these

Correct Answer :

A. Semi-conductor


Related Questions

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Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans?

A. Emissivity of pipe surface

B. Diameter & length of the pipe

C. Temperature of hot pipe surface & that of air in the room

D. None of these

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4

A pycnometer is used for the measurement of

A. Flow rate of molten metal

B. Specific gravity of a liquid

C. Composition of alloys

D. Concentration of a solution

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Which of the following is the correct nature of shear stress distribution along the cross section in a horizontal circular pipe under steady state fluid flow condition?

A.

B.

C.

D.

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4

Hydro-cyclone is a

A. Crusher

B. wet classifier

C. Dry classifier

D. Magnetic separator

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4

Pick out the wrong statement.

A. A soft magnetic material should have high permeability and small area of hysteresis loop

B. Poisson's ratio of high melting point metals is more than unity

C. Solders generally melt at less than 185°C

D. Steel produced by B.O.F process is ideally suited for manufacturing flat product

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Thermal conductivity of a material does not depend upon its

A. Mass

B. Volume

C. Surface area

D. All 'a', 'b' & 'c'

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4

For preparation of porous bearings by powder metallurgy, preferred particle shape is

A. Spherical

B. Nodular

C. Irregular

D. No preferred shape

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4

Silicon percentage in the silicon steel used for electrical appliances/equipments is

A. 0.3-0.4

B. 12-14

C. 3-4

D. 20-25

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4

With increase in impurities in metals, their corrosion resistances

A. Increase

B. Decrease

C. Remain same

D. May increase or decrease; depending on the type of metal

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4

The excess air required for the combustion of pulverised coal is of the order of about __________ percent.

A. 5

B. 15

C. 30

D. 45

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4

Which one of the following is incombustible?

A. H2

B. CCl4

C. C2H2

D. S

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4

A metal having a Poisson's ratio = 0.3 is elastically deformed under uniaxial tension. If the longitudinal strain = 0.8, then the magnitude of thickness strain is

A. -0.8

B. 0.8

C. +0.08

D. -0.24

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4

Electrometallurgy is not involved in the extraction of __________ from its ore.

A. Aluminium

B. Tin

C. Lead

D. Both (B) & (C)

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The kinematic viscosity (in stoke) and the absolute/dynamic viscosity (in poise) are the same for __________ at room temperature.

A. Air

B. Water

C. Mercury

D. Alcohol

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Which of the following materials has the maximum shrinkage allowance?

A. Brass

B. Cast iron

C. Lead

D. Aluminium alloy

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4

Speisses is a mixture of the following:

A. Arsenides of heavy metals

B. Antimonides of heavy metals

C. Arsenides & antimonides of heavy metals

D. Iron, cobalt and nickel

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4

Nitriding of a steel part does not increase its

A. Grain size

B. Fatigue limit

C. Surface hardness

D. Wear resistance

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4

Use of flux during soldering is done to

A. Increase fluidity of solder by lowering its melting temperature

B. Prevent oxide formation

C. Wash away surplus solder

D. Full up the joint gap

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4

Which of the, following is not associated with the functioning of a petrol engine?

A. Compression ignition system

B. Spark plug

C. Carburettor

D. Otto cycle

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4

__________ cannot increase the fatigue strength of a material.

A. Grain refining

B. Grain coarsening

C. Surface hardening

D. Shot peening

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4

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.

A.

B.

C.

D.

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4

Which of the following equipments is used for liquid dispersion?

A. Packed column

B. Venturi scrubber

C. Bubble cap plate column

D. Wetted wall column

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4

Dislocations are __________ defects.

A. Point

B. Line

C. Volume

D. None of these

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4

The dew point of moist air becomes __________ with decrease in its relative humidity.

A. Less than the wet bulb temperature

B. More than the wet bulb temperature

C. More than the dry bulb temperature

D. Equal to wet bulb temperature

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4

__________ can replace tungsten in high speed steel.

A. Chromium

B. Vanadium

C. Cobalt

D. Molybdenum

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4

The most important function of a washer is to provide bearing area and washers are normally specified by their hole diameters. The diameter of washer as compared to the nut is

A. More

B. Less

C. Same

D. More but less than the diameter of bolt

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4

The activity of pure hydrogen gas at 1000°C and 5 atm pressure

A. Is always less than 1

B. Is always greater than 1

C. Can be 5

D. Depends on the choice of the standard state

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4

High endurance limit of carburised machine parts is because of the fact that carburisation

A. Suppresses any stress concentration produced in the parts

B. Enhances the yield point of the material

C. Introduces a compressive layer on the surface

D. Produces a better surface finish

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4

Ferromagnetic materials owe their properties to __________ inner sub-shells.

A. Completely filled

B. Partially filled

C. Equally filled

D. Vacant

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4

The product (s) of roasting of a sulphide ore is (are)

A. Oxide only

B. Sulphate only

C. Oxide and sulphate

D. Dependent on temperature and partial pressure of oxygen & sulphur dioxide