JNTUK B.Tech R23 Engineering Physics – Important Questions
UNIT I
Short Answer Questions
- What is the significance of coherence in interference of light?
- Define diffraction grating.
- What are the types of polarization?
Long Answer Questions
- Explain how Newton’s rings are formed in reflected light. Derive expressions for diameters of dark and bright rings.
- Explain interference in thin films (reflection geometry) and derive conditions for constructive and destructive interference.
- Explain resolving power and dispersive power of a diffraction grating with derivations.
- What is double refraction? Explain the construction and working of a Nicol prism.
- Derive the expression for Fraunhofer diffraction due to a single slit and discuss the intensity distribution.
- Explain polarization by reflection and refraction. Derive Brewster’s law.
UNIT II
Short Answer Questions
- What is the significance of Miller indices?
- Define coordination number and packing fraction.
- What are Bravais lattices?
Long Answer Questions
- Determine the atomic radius and packing factor for SC, BCC and FCC lattices.
- State and explain Bragg’s law. Derive the condition for X‑ray diffraction.
- Describe the seven crystal systems with neat diagrams and lattice parameters.
- Explain Miller indices and derive an expression for inter‑planar spacing d(hkl) in cubic crystals.
- Describe Laue and powder methods for crystal‑structure determination.
- Explain an X‑ray diffractometer and its applications in structure analysis.
UNIT III
Short Answer Questions
- Define electric polarization and dielectric constant.
- What are magnetic domains?
- Differentiate between soft and hard magnetic materials.
Long Answer Questions
- Derive an expression for electronic polarizability and show that it is proportional to atomic volume.
- Derive the Clausius–Mossotti equation for dielectrics.
- Explain the atomic origin of magnetism and classify magnetic materials.
- Derive an expression for the Lorentz internal field in dielectrics.
- Explain domain theory of ferromagnetism and B‑H hysteresis curve.
- Discuss frequency dependence of polarization and dielectric loss.
UNIT IV
Short Answer Questions
- State Heisenberg’s uncertainty principle.
- What does Fermi energy represent?
- List the postulates of quantum free‑electron theory.
Long Answer Questions
- Derive Schrödinger’s time‑independent equation and solve it for a particle in a 1‑D infinite potential well.
- Explain the Fermi–Dirac distribution function and its temperature dependence.
- Derive an expression for electrical conductivity using quantum free‑electron theory.
- Explain the dual nature of matter and derive the de Broglie wavelength.
- Derive the density‑of‑states expression and discuss its significance.
- Compare classical and quantum free‑electron theories, highlighting merits and demerits.
UNIT V
Short Answer Questions
- What does the forbidden energy gap signify?
- Define Hall coefficient and state its applications.
- Differentiate between intrinsic and extrinsic semiconductors.
Long Answer Questions
- Explain energy‑band formation in solids and classify materials as conductors, insulators and semiconductors.
- Derive the carrier‑concentration expression for intrinsic semiconductors.
- Derive carrier‑concentration expressions for N‑type and P‑type semiconductors.
- Explain the Hall effect, derive the Hall coefficient and discuss applications.
- Explain drift and diffusion currents in semiconductors and derive Einstein’s relation.
- Discuss Fermi level in intrinsic and extrinsic semiconductors with temperature dependence.
Important Numerical Problems
Unit I
- Newton’s Rings: Determine wavelength or refractive index using the Newton’s‑rings setup.
- Thin Films: Calculate minimum thickness for constructive or destructive interference.
- Wave Plates: Find thicknesses of half‑wave and quarter‑wave plates.
Unit II
- Bragg’s Law: Compute wavelength, lattice spacing or diffraction angle.
- Packing Fraction: Calculate packing fractions for SC, BCC and FCC lattices.
- Miller Indices: Find inter‑planar spacing for specified (hkl) planes.
Unit III
- Polarizability: Solve for electronic or ionic polarizability values.
- Dielectric Constant: Apply the Clausius‑Mossotti relation to find εr.
Unit IV
- de Broglie Wavelength: Compute wavelengths for electrons, protons, etc.
- Uncertainty Principle: Evaluate uncertainties in position/momentum pairs.
- Particle in a Box: Calculate energy levels and associated wavelengths.
Unit V
- Carrier Concentration: Determine n and p for intrinsic/extrinsic materials.
- Hall Effect: Calculate Hall coefficient and carrier mobility.
- Conductivity: Evaluate electrical conductivity at different temperatures.