Materials and Components Questions

• The conductivity of intrinsic semiconductor is given by
• Material which lack permanent magnetic dipoles are known as
• If e is the charge of an electron, R is the radius of its orbit and ω is the angular velocity of electron, the magnetic dipole moment μm of the orbit is |μm| = eωR2.
• Above ferroelectric curie temperature, spontaneous polarization in ferroelectric materials becomes stronger.
• If n denotes principal quantum number, the angular quantum number l = 0, 1... (n - 1).
• For a permanent magnetic material
• A parallel plate capacitor has its length, width and separation doubled. It fringing effects are neglected, to keep the capacitance same, the dielectric constant must be
• Hydrogen is used in
• In a coaxial cable, braided copper is used for
• Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm2 of surface. Reason (R): Thermionic emission current is given by Ith = SA0 T2 e-Ew/kT.
• Assertion (A): From the slope of the line in Figure, we can find permanent dipole moment of the molecules. Reason (R): Total polarization of a polyatomic gas is given by P = N(ae + ai + μ2p / 3kT)E.
• Assertion (A): Electronic and Ionic polarization in a polyatomic gas are independent of temperature. Reason (R): The orientation polarization is independent of temperature.
• In atomic physics, a state with l = 0 is called p state.
• Assertion (A): In a perfect capacitor, the current density is given by ω ∈0E0∈'rcos(ωt + 90°), where ∈r' is real part of dielectric constant. Reason (R): In a perfect capacitor, dielectric losses are zero.
• The attraction between the nucleus and valence electron of copper atom is
• The minority carrier life time and diffusion constant in a semiconducting material are 100 μs and 100 cm2/s respectively. The diffusion length of carriers is
• If a sample of germanium and a sample of silicon have the same impurity density and are kept at room temperature
• For a paramagnetic material, susceptiblity increases with increasing temperature.
• If a piece of wood is placed in a magnetic field
• Assertion (A): For Diamond, μr = 1 Reason (R): Diamond is a diamagnetic material.