Materials and Components Questions

• The maximum temperature limit of class B insulation is
• Resistivity of metals consists of two parts, one part constant and the other temperature dependent.
• Assertion (A): The regular or irregular stacking of atoms has importanteffect on properties of materials. Reason (R): The arrangement of atoms in a given material can be studied using X-rays.
• Assertion (A): Both sodium and ferrous are ferromagnetic. Reason (R): Both sodium and ferrous have body centred cubic structure.
• Assertion (A): ∈0 has the dimensions of farad per meter. Reason (R): D = ∈0∈r E.
• Assertion (A): Drift velocity of electrons is proportional to the applied electric field E. Reason (R): The average drift velocity per unit field is called mobility.
• For iron, the ferromagnetic Curie temperature is
• In a valence crystal, the valence electrons
• The probability of recombination of electrons and holes in a semiconductor is proportional to
• A photoconductor is a
• Dielectric constant, under the condition of alternating fields, is a complex quantity.
• The amount of time between the creation and recombination of a free electron and hole is called
• In ferromagnetic materials, the orientation between neighbouring permanent dipoles is parallel.
• As regards dielectric constant εr
• Assertion (A): Electron concentration n, hole concentration p and charge concentration ni are related by ni2 = np. Reason (R): p type semiconductor is obtained by adding trivalent impurity to intrinsic semiconductor.