Materials and Components Questions

• Magnetic ordering in ferrimagnetic materials Ferrimagnetic materials have anti-parallel orientation of equal magnetic dipole moments. Is this statement correct?
• Ordering materials by decreasing magnetic permeability (μr) Consider the following materials: 1) Nickel, 2) Silver, 3) Oxygen, 4) Aluminium. Arrange them in the order of decreasing relative permeability μr (highest first).
• Fundamental physical constants: masses of the proton and the electron In atomic and solid-state physics, it is common to recall the standard rest masses of the proton and the electron. Choose the correct pair (proton mass, electron mass) in SI units (kilograms).
• Energy of an induced electric dipole If an atom with scalar polarizability α is placed in a uniform electric field of magnitude E, is the potential energy associated with the induced dipole equal to 0.5 * α * E^2?
• Larmor precession: frequency shift in a magnetic field An electron orbits with angular frequency ω0 in the absence of a magnetic field. When a uniform magnetic field B is applied, the orbital frequency becomes approximately ω ≅ ω0 + (e / (2m)) * B, where e is the magnitude of electron charge and m its mass. Is this statement acceptable as written?
• Automotive ignition coils: governing electromagnetic principle Traditional spark-ignition systems in automobiles step up 12 V battery voltage to tens of kilovolts to produce a spark. Which principle enables this voltage transformation in the ignition coil?
• Magnetic materials and retentivity Materials with low retentivity (low remanent magnetization after removal of the magnetizing field) are most suitable for which application?
• Germanium (Ge) as a group-IV element How many valence electrons does a germanium atom have in its outer shell?
• Einstein relation: mobility–diffusion conversion at 300 K A semiconductor has carrier mobility μ = 0.40 m^2/(V·s) at 300 K. Using the Einstein relation, compute the diffusion constant D (in m^2/s), taking kT/q ≈ 0.026 V at 300 K.
• Field-line visualization: do magnetic field lines attract each other? Evaluate the statement: “Lines of magnetic field attract each other.” Choose the most accurate scientific assessment.
• Temperature dependence of the temperature coefficient in metals Near room temperature and over a moderate range, how does the temperature coefficient of resistance α for a typical pure metal behave as temperature increases?
• Polarization of a homogeneous linear dielectric For a homogeneous, linear, isotropic dielectric in an electric field E, is the polarization (dipole moment per unit volume) given by P = ε0 * (εr − 1) * E?
• Superconductivity basics in materials science What is the standard term for the temperature at which certain materials undergo a transition to the superconducting state (zero electrical resistance and Meissner effect)?
• Dielectric loss in a lossy capacitor under sinusoidal excitation A parallel-plate capacitor has C = 200 × 10^-12 F and dielectric loss tangent tanδ = 4 × 10^-4. It is energized at frequency f = 10^6 Hz with a sinusoidal voltage of peak value 2 V. Calculate the dielectric power loss (in watts), using V_rms and the relation P ≈ V_rms^2 * ω * C * tanδ.
• Thermal behavior of ferromagnets above Curie temperature State whether the following is correct: When the temperature exceeds the ferromagnetic Curie temperature, a ferromagnetic material behaves like a paramagnetic material.
• Quantum numbers that label electron states in atoms Which set lists the standard symbols for the three quantum numbers commonly used to describe an electron's state (principal, azimuthal/orbital, and magnetic, excluding spin)?
• Comparative dielectric strength of common insulating media Among the following, which typically exhibits the lowest dielectric strength under comparable conditions of thickness and environment?
• Insulating liquid used in power and distribution transformers Identify the standard insulating and cooling liquid commonly used as transformer oil in electrical power apparatus.
• Alloy scattering and resistivity change — adding a small percentage of Cu to Ni Copper has lower resistivity than nickel. When a small percentage of Cu is alloyed into Ni, how does the resistivity of the resulting Ni–Cu alloy change and why?
• Perfect diamagnetism in superconductors (Meissner state) For an ideal superconductor in its superconducting state, what is the relationship between magnetisation M and applied magnetic field H (SI units), assuming B = μ0 (H + M) and complete flux expulsion?