Materials and Components Questions

• The chemical properties of atoms are determined by all the electrons and their configuration.
• If k is Boltzmann's constant and T is absolute temp, then at room temp.
• From a homogeneous and isotropic dielectric material of dielectric constant ∈r, a small volume element is taken out creating a cavity. The field can be kept homogeneous if Di. (i.e., electric flux density inside the cavity) and D0 (i.e., electric flux density outside the cavity) are such that
• At T = 0, the resistivity of a perfect single crystal of a metal is
• The iron core of a coil is removed so that it becomes an air cored coil. Its inductance will
• In a metal the probability of a state 0.1 eV below Fermi level being occupied
• When a ferromagnetic substance is magnetised there are small changes in dimensions. This phenomenon is called
• Electrical conductivity of metals expressed in ohm-1 m-1 is of the order of
• In a polyatomic gas, the types of polarization which exist together are
• In elemental dielectrics, the orientation and ionic polarization are absent.
• An electron in a homogeneous magnetic field and having velocity perpendicular to the direction of field moves
• An homogeneous dielectric material is subjected to an electric field E. If a small cavity is made inside the material, the electric field intensity inside and outside the cavity are different.
• A particle of charge Q coulombs is bound elastically to an equilibrium position with a force constant of f newton per metre. The polarizability of the system is
• In an hydrogen atom, an electron moves in the field of a proton. The stability of orbit requires equilibrium between coulomb's force and centrifugal force.
• An electron shell corresponding to principal quantum number n can contain a maximum of
• Assertion (A): Dielectric losses are proportional to tan δ. Reason (R): tan δ = where ∈r' and ∈r" denote the real and imaginary parts of ∈r.
• Spontaneous polarization occurs in ferroelectric materials.
• For a core having a relative permeability μr, magnetic dipole moment per unit volume M and field strength H, the flux density B is
• Figure shows a composite capacitor. If CA, CB, CC are the capacitances of capacitors A, B, C, the overall capacitance C is
• Assertion (A): In some materials, ∈r is independent of temperature while in others, ∈r depends on temperature. Reason (R): If permanent dipoles are absent, ∈r varies with temperature.