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Current Affairs January 2024

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4

Pick out the wrong statement.

A. A ferromagnetic material becomes paramagnetic above the 'Curie temperature'

B. Permanent magnets are made of hard materials, whereas electromagnets require soft magnetic materials

C. Soft magnetic materials (e.g., pure iron) have higher permeability and low hysterisis loss and coercive forces

D. Tungsten steel and alnico are not hard magnetic materials

Correct Answer :

D. Tungsten steel and alnico are not hard magnetic materials


Related Questions

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4

The specific gravity of coal depends mainly on its __________ content.

A. Carbon

B. Volatile matter

C. Ash

D. Moisture

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4

__________ of test specimens is not involved in any hardness testing method.

A. Fracture

B. Indentation

C. Wear

D. Scratch

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4

Steel balls are manufactured by

A. Sintering

B. Casting

C. Cold heading

D. Spinning

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4

Thermal efficiency of an internal combustion engine is around __________ percent.

A. 8

B. 35

C. 65

D. 80

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4

Resilience of a bolt can be increased by increasing its

A. Length

B. Shank diameter

C. Head diameter

D. None of these

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4

Which of the following pairs is not correctly matched?

A. Uranium - 233 : Fertile material

B. Binding energy : Mass defect

C. Scattering: Absorption cross-section

D. Number of nucleons : Mass number

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4

Internal energy of a gas obeying Van-Der- Waals equation of state, [p + (a/v2)] (V - b) = RT, depends upon its

A. Pressure & temperature

B. Pressure & specific volume

C. Temperature & specific volume

D. Temperature only

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4

Vibration upto 100 kilo hertz can be most accurately measured by a __________ type accelerometer.

A. Preloaded spring

B. Piezoelectric

C. Bonded strain gauge

D. None of these

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4

Current employed in resistance welding ranges from __________ kVA/.

A. 1.2 to 2.5

B. 4.5 to 6.2

C. 7.5 to 8.5

D. 10.5 to 15.5

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4

The most important requirement for aluminium industry is the availability of cheap

A. Ore

B. Electrical power

C. Labour

D. Abundant water

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4

Unit of viscosity in CGS system is

A.

B.

C.

D.

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4

The most commonly used moderator in nuclear power plants is

A. Graphite

B. Light water

C. Heavy water

D. Beryllium

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4

Work done by a/an __________ process is determined by ∫p. dv

A. Adiabatic

B. Quasi-static

C. Isothermal

D. Isentropic

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4

Metal shots used in shot blasting are made of

A. Stellite

B. Steel

C. Bronze

D. Lead

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4

Surface tension of a liquid

A. Is due to intermolecular forces of cohesion

B. Decreases with rise in temperature

C. Is responsible for the spherical shape of an isolated liquid drop

D. All (A), (B) & (C)

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4

Blast furnace slag is mainly molten

A. Sand

B. Magnesium silicate

C. Calcium silicate

D. Iron pyrite

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4

Fire in fuel gas pipelines is extinguished most effectively by

A. Spraying water

B. Blanketting the area with nitrogen atmosphere

C. Fire fighting foam

D. None of these

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4

Tin based white metals are used, where bearings are subjected to

A. High pressure & load

B. Low pressure & load

C. High temperature

D. Large surface wear

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4

Good design of the casing of a centrifugal pump aims at minimising the

A. Cavitation

B. Frictional losses

C. Kinetic energy loss

D. Static head

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4

Other parameters remaining same, the recrystallisation temperature of an alloy is lowered, when

A. Strain rate is increased

B. Grain size is increased

C. Prior cold deformation is increased

D. Not affected by any of the above parameters

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4

In multipass welds, shot peening is done after each pass to

A. Close the surface porosity

B. Break the continuity of columnar grains

C. Flatten the weldment

D. Introduce texture in the weld

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4

Which of the following relationships is correct for relating the three elastic constants of an isotropic elastic material (where, E = Young's modulus, G = Modulus of rigidity or shear modulus v = Poisson's ratio)?

A. E = 2G (1 + v)

B. E = G (1 + v)

C. E = G (1 + v)/2

D. E = 2G (1 + 2v)

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4

__________ joint is usually used for joining cast iron pipes mostly used for temporary pipelines, where it may be necessary to dismantle & reassemble the pipeline very frequently.

A. Collar

B. Flanged

C. Bell and Spigot

D. Expansion

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4

The most suitable material for die casting is

A. Iron

B. Copper

C. Steel

D. Nickel

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4

With increase in temperature, the electrical conductivity of semiconductors

A. Increases

B. Decreases

C. Remain constant

D. Either (A) or (B), depends on the type of semi-conductor

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4

Heat required to raise the temperature of a body by 1 °C is called its

A. Heat capacity

B. Specific heat capacity

C. Thermal conductivity

D. Water equivalent

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4

Carbide tipped cutting tools are manufactured by powder metallurgy techniques and have a composition of

A. 90% tungsten carbide and 10% cobalt

B. 70% aluminium oxide & 30% silica

C. 30% nickel, 15% chromium & 55% tungsten

D. 65% tungsten & 35% zirconium

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4

Pick out the wrong statement.

A. Seam welding, projection welding & spot welding are the classification of electrical resistance welding

B. Electrode tip in spot welding is of copper and the tip diameter should be equal to t (where, t = plate thickness to be welded)

C. In spot welding, two pieces to be joined are overlapped and placed between two electrodes

D. Mild steel sheet cannot be spot welded

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4

Wrought iron does not have

A. Uniform strength in all directions

B. Ability to hold protective coating

C. High ductility & corrosion resistance

D. Easily weldable characteristics

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4

Sacrificial anode method is used in the protection of pipelines which are buried underground. Sacrificial anode

A. Occurs higher in the electro-chemical series of metals

B. Is exemplified by magnesium plate

C. Is much cheaper than the cathodic base material to be guarded against corrosion

D. All (A), (B) & (C)