Electrical and Electronic Materials (EX-504 (C)) - Important Questions

Explain the properties, classification and commonly used types of conducting materials.

Describe the crystal structure of materials.

Distinguish between metals and alloys.

Explain the different types of resistors and conductor materials, including bus bar materials, used in electrical machines.

Explain classification of solids from electrical point of view.

Discuss the classification of engineering materials in detail.

Write short notes on ferrous and non-ferrous alloys, underground cable conductors, dielectric strength and loss, and $SF_6$ gas specification for GIS.

Explain ceramic materials with examples.

Explain zone refining and crystal growth, including the Bridgman technique.

Find the current through a copper wire given length, area, voltage, electron mobility, charge and number density.

Prove that in conducting materials $\frac{1}{\mu_c} = \frac{1}{\mu_I} + \frac{1}{\mu_L}$ for overall, ionized impurity scattering limited, and lattice vibration scattering limited mobilities.

Describe the classes/types of insulating materials.

What are insulating materials? Write their properties.

Explain piezoelectricity and ferroelectricity.

Describe the testing for transformer oils.

What are dielectric loss and dissipation factor and what factors affect dielectric loss?

Define dielectric loss, dissipation factor and dielectric strength.

Define dielectric loss and dissipation factor.

What is meant by polarization and what are its different types?

Given electronic polarizability and density, find the static dielectric constant of solid Ar.

Explain various factors affecting dielectric strength.

Given number density, dipole moment and electric field, find polarization, electric susceptibility and relative permittivity.

What is the Hall effect? Derive the expression for the Hall coefficient for an n-type semiconductor and state its applications/importance, with diagrams.

Draw and explain the energy band diagrams for different materials (conductors, semiconductors and insulators).

Compare intrinsic and extrinsic semiconductors.

Define semiconductor laser and discuss its characteristics and applications.

Explain/discuss the working of photoconductive cells and photovoltaic cells.

Derive an expression for the electron carrier concentration in an intrinsic semiconductor.

Write short notes on phototransistors and light dependent resistors (LDR).

Write short notes on: a) LCD; b) Polymers; c) Hall effect; d) Register types.

Define trivalent impurities and give applications of semiconductors.

Explain the electronic properties of Gallium Arsenide and Gallium Phosphide.

Differentiate between photoconductive and photovoltaic cells.

Explain hard and soft magnetic materials (including on the basis of magnetic susceptibility).

Explain and compare ferromagnetism and antiferromagnetism, with suitable diagrams.

Classify and compare diamagnetic, paramagnetic and ferromagnetic materials with their properties.

Explain the factors affecting permeability and hysteresis.

A Solenoid of $500$ turns per meter is carrying a current of $3 A$. Its core is made of iron, which has a relative permeability of $5000$. Determine the magnitudes of magnetic intensity, magnetizations and magnetic field inside the core.

What is superconductivity? Explain superconductivity and its applications.

Explain $SF_6$ gas, its advantages and applications including use in GIS.

What are ultralight materials and metallic foams? Explain.

Write the physical and electrical properties of $SF_6$ gas.

What are nanomaterials and ultra-light materials?

Numerical on temperature dependence of critical field: given critical fields at two temperatures, calculate transition temperature $T_c$ and critical field at $0\,K$.

Discuss nanomaterials in brief.

What is Meissner effect? Describe Type-I and Type-II superconductors and their applications.

What is superconductivity? Explain critical temperature, critical field and critical current density with necessary diagram.

Write short notes on the following (any two):