HomeElectrical material objective QuestionElectrical material objective Question Electrical material objective Question Education April 08, 2023 0 1➤ In the magnetic core the electromotive forces (emf) induced in accor- dance with Faraday's law of electromagnetic induction give rise to field current.armature current.excitation currenteddy current2➤ The important considerations to be made in selection of materials is /areEase of fabrication Availability CostAll of these3➤ The converse of magnetostriction effect isVillari effectSkin effectSee back effectSkin effect 4➤ Which of the following inductors will have the least eddy current losses?Wooden coredAir cored Iron coredLaminated iron cored5➤ When a ferromagnetic substance is magnetized the phenomenon of 'magnetostrictriction' causesSmall changes in its dimensions Change in permeability of the substance Decrease in saturation flux-densityIncrease in the body temperature 6➤ Conductivity of aluminium is _______time of copper2.50.60.41.63 7➤ Which one of the following materials has temperature coefficient of resistance very close to zeroNichromeCarbon MaganinAluminium 8➤ Platinum is employed inElectrical contacts and thermocouple Grids for special purpose vaccum tubesAll of theseHeating elements for electric furnace 9➤ High frequency transformer cores are generally made fromMu-metalCobaltNone metalFerrites10➤ Wire wound resistances are used only whenHigh power rating is necessary Precision is essential Low values are required Costly equipment are manufactured 11➤ Maximum flux density in cold rolled grain Oriented steel is2.01.51.10.512➤ The shape B-H curve for air gap is ParabolaEllipseStraight line Sinusoidal 13➤ Total number of electrons that can be accommodated in various electron states in a valance band of given solid is equal toAtomic number of solidThe number of atoms in the solidHalf of number of atoms in solidAll of these14➤ The coordination number of a cubic structure is862415➤ The difference between the number of atoms in a unit cell of a BCC crystal and FCC crystal is146216➤ What type of defects causes F-centers in a crystal Stoichiometric defectMetal excess defects due to anion vacancies Frenkel effectMetal excess defect due to extra cations17➤ In ionic crystal electrical conductivity isPractically zeroDepends on temperature Very highDepends on material 18➤ In. Crystal lattice what are the vacancies created by the absence of certain things atoms known asHertz defectPauli defectsSchottky defectsCrystal defects 19➤ Epitaxial III-V group semiconductor compounds have which one of the following crystal structure?BCCZinc blendsFCCHexagonal 20➤ Specific resistance of a conductor depends uponDimensions of the conductor Composition of conductor material Both a and bResistance of conductor SubmitYour score is Tags Electrical material objective Question Newer Older