Electrical material Ques part 2

1➤ Pure metals generally have

High conductivity and large temperature coefficient Low conductivity and zero temperature coefficient Low conductivity and high temperature coefficient High conductivity and low temperature coefficient

2➤ What is the magnetic susceptibility of an ideal super conductor?

1-1Infinity 0

3➤ The dc resistivity and permeability exhibited by a type 1 super conductor are respectively

0,00,11,11,0

4➤ The materials not having negative temperature coefficient of resistivity are

SemiconductorsMetalsInsulators All of these

5➤ If the diameter of a copper wire is increased by two times keeping it's terminal voltage same,then the drift velocity will

Remains unchanged Becomes twiceBecome halfBecomes four times

6➤ Bohr magneton is unit of

Magnetic energy PolarisibilityHysteresis lossPermanent dipole moment due to spin

7➤ Enameled wires are preferred to cotton-covered wires to

Reduce the resistivity Improve heat dissipation Withstand higher temperature All of these

8➤ Magnetic field of earth has no vertical component at

Magnetic equatorLongitude 45°Latitude 45°Magnetic poles

9➤ All magnetic material lose their magnetic properties when

Cooled at low temperature Kept in an aluminium boxKept in vaccumHeated to high temperature

10➤ Ferromagnetic property may be explained on the basis of

Domain theoryFaraday's theory Curie-weiss theoryEinstein theory

11➤ When the temperature of magnetic material is raised above the Curie temperature, it behaves similar to

Diamagnetic material Paramagnetic material Ferrimagnetic materials Antiferromagnetic materials

12➤ Orbital magnetic moment of an electron, in an atom, is of the order of

1.0 Bohr magneton 0.1 Bohr magneton 10 Bohr magneton 100 Bohr magneton

13➤ A permeable substance is one

Which is strong magnetic Which is weak magnetic Through which magnetic lines of force passes easilyWhich is good conductor

14➤ Exposure of insulating material to moisture causes increase in

Dielectric strength Dielectric lossInsulation resistance All of these

15➤ The ceramic dielectric used in electrical engineering include

Cermetvand silicideSilicide and cordierite Porcelain and cermetPorcelain and cordierite

16➤ Iron is a

Ferromagnetic Ferrimagnetic Antiferromagnetic Paramgnetic

17➤ With the increase in temperature magnetic susceptibility of a ferromagnetic materials will

Decrease Increase Increase initially and then decrease Reamains constant

18➤ Paramagnetic susceptibility of a material

Increase linearly with temperature Decrease linearly with temperature Decrease linearly with (1/T)Increase linearly with(1/T)

19➤ Which one of the following is not a ferromagnetic materials

CobaltBismuth IronNickel

20➤ Air exhibits

ParamagnetismFerromagnetismFerrimagnetismAntiferromagnetism

21➤ The magnetic field require to reduce the residual magnetization to zero is called

Retentivity Hysteresis Coercivity Saturation

22➤ On which of the following factors does hysteresis loss not depend?

Neel temperature Frequency of the fieldVolume of the material Magnetic field intensity

23➤ Commonly used dielectric in electrolytic capacitors is

All of the belowCadmium nitrideMagnetism oxideAluminium oxides

24➤ _______is employed for winding of coils for DC motor starters

ConstantanCopperNichromeAluminium

25➤ Which one of the following is not a permanent magnetic material

Silicon iron AlnicoCobalt steelChromium steel

26➤ Mettalic copper is

Paramgnetic substance Ferromagnetic substance Diamagnetic substance Ferrimagnetic substance

27➤ The coercive force in a ferromagnetic materials is related to

Area enclosed by B-H loopIntercept on the positive B axis of The B-H loopIntercept on the negative B axis of The B-H loopMaximum value of B on B-H loop

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