Materials and Components Questions

• Which circuit element exhibits electrical “inertia,” i.e., opposition to changes in current rather than to the current itself?
• True/False (Bonding): In a purely covalent (valence) crystal, the bonding between atoms is accomplished by sharing valence electrons.
• Units check: What are the units of the permeability of free space μ₀ and the relative permeability μ_r?
• Assertion–Reason (Fermi–Dirac statistics): At any nonzero temperature, the probability that an energy state E equal to the Fermi level E_F is occupied equals 0.5. Reason: The Fermi–Dirac function f(E) = 1 / (1 + exp[(E − E_F) / (kT)]) gives f(E_F) = 1 / (1 + exp(0)) = 0.5.
• If two resistive materials with temperature coefficients of resistance 0.004 and 0.0004 per °C are connected in series, what is the overall temperature coefficient for the series combination?
• If the diameter of a circular wire is doubled while using the same permissible current density, its current-carrying capacity becomes what multiple of the original value?
• As the temperature of a pure silicon specimen is increased
• When a material becomes a superconductor, its resistivity becomes
• In metals the thermal conductivity K and electrical conductivity σ are related as (K/σT) = L, L is known as
• In metals, the average drift velocity of electron per unit field is called mobility.
• Silicon and germanium atoms combine orderly into array of atoms located in repetitive geometric pattern. This pattern is called
• Dielectric constant of transformer oil is about
• In carbon resistor colour code, the third band is red. It indicates
• Assertion (A): In many materials, dielectric polarization causes mechanical distortion. Reason (R): If dielectric polarization causes mechanical distortion then mechanical distortion must cause dielectric polarization.
• Consider the following statement If an electric field is applied to an n type semiconductor bar, the electrons and holes move in opposite directions due to their opposite charges. The net currents is both due to electrons and holes with electrons as majority carriers sum of hole and electron currents difference between electron and hole currents. Which of above statements are correct?
• Assertion (A): ∈r can be determined experimentally by measuring the capacitance of a parallel plate capacitor with and without the dielectric. Reason (R): Capacitance of a parallel plate capacitor = .
• The magnetic moment in units of Bohr magneton of a ferrous ion in any ferrite is
• Assertion (A): The optical dielectric constant (i.e., εr at optical frequencies)of ionic dielectrics is less than static dielectric constant. Reason (R): At optical frequencies, Pi = 0.
• In a homogeneous magnetic field H of a solenoid, the core carries a magnetic dipole moment M per unit volume equal to
• In molecules of ionic crystals, orientation polarization is zero.