Physics Questions: Radiation, Waves, Optics, Lasers, and Nanoscience
English with a size of 1.34 MBThermal Radiation and Quantum Concepts
Q) Wien's displacement law
Q) What is Wien's displacement law? 
Q) de Broglie wave at temperature T
Q) What is the de Broglie wave for a moving particle at temperature T? 
Q) Assumptions used by Planck
Q) State the assumptions made by Planck to explain the black-body radiation curve. 
Q) Wave packet in quantum mechanics
Q) Describe the term wave packet in quantum mechanics. 
Q) Physical significance of wave function
Q) What is the physical significance of the wave function? 
Q) Postulates of Planck's law
Q) Explain the basic postulates of Planck's law of radiation. 
Q) Compton effect with visible light
Q) Can the Compton effect be observed with visible light? Explain briefly. 
Q) Davisson–Germer experiment objective
Q) What was the objective of conducting the Davisson–Germer experiment? 
Q) Planck's spectral energy density
Q) Write down Planck's expression/formula for spectral energy density in black-body radiation. 
Q) Skin depth calculation example
Q) An electromagnetic wave of frequency 10 MHz is incident normally on a good conductor (e.g., copper) with conductivity σ = 5.8 × 10^7 S/m and relative permeability μr = 1. What is the skin depth δ of the wave in the conductor? (Use μ0 = 4π × 10−7 H/m) 
Q) Explain skin depth
Q) Explain the term skin depth with necessary formulae. 
Q) Maxwell's modification of Ampère's law
Q) Why did Maxwell propose the modification of Ampère's law? 
Q) Physical significance of Poynting vector
Q) Write down the physical significance of the Poynting vector. 
Q) Conduction vs displacement current
Q) Differentiate between conduction current and displacement current. 
Q) Continuity equation (differential)
Q) Write down the expression for the continuity equation in differential form. 
Interference, Diffraction and Resolution
Q) Dispersive power of a grating
Q) Define the dispersive power of a grating. 
Q) Centre dark in Newton's rings
Q) The centre is dark in Newton's rings experiment. Explain it. 
Q) Thick film shows no color
Q) A thick film shows no color in interference. Why? 
Q) Rayleigh's criterion of resolution
Q) Explain Rayleigh's criterion of resolution. 
Q) Slit smaller than wavelength
Q) What happens if the slit is smaller than the wavelength in a diffraction pattern? 
Q) Interference from independent sources
Q) Why cannot two independent light sources produce an interference pattern? 
Q) Effect of many slits on diffraction
Q) What changes occur in the diffraction pattern if the number of slits is increased? 
Q) Coherent sources meaning
Q) What do you understand by coherent sources? 
Q) Population inversion (first mention)
Q) What do you mean by population inversion? 
Lasers, Optical Fibers and Superconductivity
Q) Numerical aperture of a fiber
Q) A fiber made of silicon has a core and cladding with refractive indices of 1.40 and 1.37. Find the numerical aperture of the fiber. 
Q) Spontaneous vs stimulated emission
Q) Differentiate between spontaneous emission and stimulated emission. 
Q) Cutoff parameter and number of modes
Q) State the formula to calculate the cutoff parameter and the number of modes in the fiber. 
Q) He–Ne vs ruby laser
Q) How can you say that the He–Ne laser is superior to the ruby laser? 
Q) Step-index vs graded-index fiber
Q) How is a step-index fiber compared with a graded-index fiber? 
Q) Vortex state in superconductivity
Q) What is the vortex state of superconductivity? 
Q) Scattering loss in optical fiber
Q) What do you mean by scattering loss in an optical fiber? 
Quantum Emission, Modes and Nanostructures
Q) Stimulated emission in a laser
Q) What do you understand by stimulated emission of radiation in a laser? 
Q) Population inversion in a laser
Q) Define the population inversion in a laser. 
Q) Single-mode vs multi-mode fiber
Q) State any two differences between single-mode and multi-mode step-index fiber. 
Q) Perfect diamagnetism in superconductors
Q) Show that perfect diamagnetism is an essential property of a superconductor. 
Q) Quantum well and quantum wire
Q) Discuss the terms quantum well and quantum wire. 
Q) Top-down and bottom-up methods
Q) What are the top-down and bottom-up methods? 
Q) Quantum confinement effect
Q) Explain the quantum confinement effect in nanomaterials. 
Q) What is a quantum well?
Q) What do you mean by a quantum well? 
Q) Applications of nanomaterials
Q) Write down any two applications of nanomaterials. 