Physics Most Important Questions or Topics

Physics Most Important Questions or Topics

 Displacement Current 

Question: Write the similarities and dissimilarities between conduction and displacement current. (2021-22) View

Question: State the Wien's displacement law. (2021-22) View

Question: Differentiate between conduction current and displacement current. (2022-23) View

Question: What do you understand by Displacement current ? (2022-23)

 Question: What is Displacement Current? (2020-21) View

Question: Find the conduction current density and displacement current density for a solid with conductivity, σ=10^-3  S/mand εr=2.5. Electric field intensity, E= 4.5 x 10^-6 sin (10^9t). (2020-21)

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Skin Depth

Question: Define the concept of Skin depth for high and low frequency waveforms. (2021-22)

Question: Find the skin depth δ at a frequency of 3.0 x 10^6 Hz in aluminium where 

σ = 38.0 x 10^6 S/m and µr=1. (2021-22)

Question: Define skin depth. Write the necessary formula for the skindepth for  conducting and non - conducting media . Calculate the skin depth for silver at 10^8 Hz frequency. Given - for silver µ=µ0, µ0=4π x 10^-7 N/A² , σ=3 x 10^7 mhos/m. (2022-23)

Question: What do you understand by skin depth? (2022-23) View

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Compton Effect and Compton shift

Question: What is Compton effect and Compton Shift? (2021-22)

Question: What is Compton effect? Deduce an expression for Compton shift. (2021-22)

Question: Can Compton effect be observed with visible light? Explain briefly. (2022-23)

Question: Derive an expression for Compton wavelength shift (Δλ) for a Compton scattering experiment. The wavelength of an X-ray photon is doubled on being scattered through 90° with a carbon block in a compton Experiment. Find out the wavelength of the incident photon. (Electron mass =9.1x 10^-3 kg, Planck's constant h= 6.63 x 10^-34 m²kg/s, speed of light c=3.0 x 10^8 m/s). (2022-23)

Question: Discuss Compton effect and derive an expression for Compton shift with the help of suitable diagram. (2020-21)

Question: What is Compton effect? Derive an expression for Compton shift. (2020-21)

Question: What is Compton effect? How does it support the photon nature of light? (2019-20)

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Schrodinger Wave Equation 

Question: What is the physical significance of the wave function? Derive Schrodinger time independent wave equation. (2021-22)

Question: Write the Schrodinger's wave equation for a particle in one dimensional box and solve it to obtain the eigen values and eigen functions. (2021-22)

Question: Solve Schrodinger equation for a free particle in one dimensional box and show that the energy eigen values are discrete. An electron is trapped in one dimensional region of length 1.0A. Find the amount of energy that must be supplied to excite the electron from ground state to first excited state. (2022-23)

Question: Derive time independent Schrodinger wave equation. Write down the time independent Schrodinger equation for a particle in one-dimensional box (infinitely deep potential well) and find out the energy eigen functions (normalized wavefunctions) of the particle. (2022-23)

Question: What are the conditions and limitations, a wave function must obey? Derive time independent Schrodinger equations. (2020-21)

Question: What is wave function? Derive time independent Schrodinger wave equation. (2020-21)

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Maxwell Equations and their physical significance

Question: Deduce the Maxwell's equations for free space and prove that electromagnetic waves are transverse in nature. (2021-22)

Question: Derive equation for simple plain electromagnetic wave starting from Maxwell's equations in free space. Show that the electromagnetic wave in free space is transverse in nature in nature.(2022-23)

Question: Derive the Maxwell equations in differential form and integral form with physical significance. (2020-21)

Question: Write Maxwell's equations in free space. Also show that the electric and magnetic vectors are normal to the direction of propagation of the electromagnetic wave.(2020-21)

Question: Deduce four Maxwell equations in free space . Explain the concept of displacement current and show how it led to modification of Ampere law. (2019-20)

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Poynting vector, Poynting Theorem and physical significance of last equation

Question: Define the Poynting vector and write its unit. (2021-22)

Question: State and prove the Poynting theorem. Show that E/M =377 Ohm. (2021-22)

Question: Prove the Poynting theorem in electrodynamics and explain the physical siginificance of each of the term appearing in the final expression of the theorem. (2022-23)

Question: What is Poynting vector? 

How is the poynting theorem derived from Maxwell equations? (2020-21) View

Question: State and deduce Poynting theorem for the flow of energy in an electromagnetic field. Discuss the physical significance of Poynting theorem.(2020-21)

Question: State and deduce Poynting theorem for the flow of energy in an electromagnetic field. (2019-20)

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Acceptance angle and Numerical aperature 

Question: What do you mean by acceptance angle and cone for an optical fiber? (2021-22)

Question: A silicon optical fibre with a core diameter large enough has a core refractive index of 1.50 and a cladding refractive index 1.47. Determine -: (i) the critical angle at the core cladding interface, (ii) the numerical aperture for the fibre , (iii) the acceptance angle in air for the fibre. (2021-22)

Question: What do you mean by acceptance angle and numerical aperature? Derive the expressions for acceptance angle and numerical aperature. (2021-22)

Question: Define the relative refractive index  difference of an optical fibre. Show how it is related to numerical aperature .(2022-23)

Question: Find out the expression for acceptance angle and numerical aperature of an optical fiber in terms of the refractive index of core and cladding. (2022-23)

Question: A glass clad fiber is made with core glass of refractive index 1.5 and the cladding is dopped to give a fractional index difference of 0.0005. Find: (a)The cladding index. (b) The critical internal reflectional angle, (c) The numerical aperture. (2020-21)

Question: Derive expressions for acceptance angle and numerical aperture. (2020-21)

Question: Explain acceptance angle and acceptance cone of fiber? Define numerical aperature. (2019-20)

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Soap Film 

Question: White light is incident on a soap film at an angle of sin^-1 (4/5) and the reflected light is observed with a spectroscope. It is found that two consecutive dark bands correspond to wavelengths 6.1x10^-5 cm and 6.0x10^-5 cm. If the refractive index of the film is 4/3, calculate the thickness. (2021-22)

Question: Calculate the thickness of a soap bubble thin film that will result in constructive interference in reflected light. The film is illuminated with light of wavelength 5000 Ă and the refractive index of the film is 1.45. (2020-21)

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Newton's rings

Question: Why the center of Newton's ring in reflected system in dark? (2021-22)

Question: Newton's rings are observed in reflected light of wavelength 5900A. The diameter of 10th dark ring is 0.50cm. Find the radius of curvature of the lens. (2021-22)

Question: Discuss the formation of Newton's rings. Show that the diameters of the bright rings are proportional to the square root of odd natural numbers. (2021-22)  

Question: Describe how Newton's ring experiment can be used to determine the refractive index of a liquid. (2022-23)

Question: A light source of wavelength 6000Ă is used along wih plano-convex lens with the radius of curvature equal to 100cm in a Newton's ring arrangement. Find out the diameter of the 15th dark ring. (2020-21)

Question: Describe the formation of Newton's rings in monochromatic light. Show that in reflected light, the diameters of dark rings are proportional to the square roots of natural numbers. (2020-21)

Question: Describe and explain the formation of Newton's rings in reflected monochormatic light. Deduce the neccessary expression for bright and dark rings. (2019-20)

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Group velocity and Phase velocity

Question: Distinguish between group velocity and phase velocity. Establish a relation between them in a dispersive medium. What will be relation between these velocites in non- dispersive medium? (2022-23)

Question: What do you understand by phase velocity and group velocity of waves? (2022-23)

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Superconductivity and superconducters 

Question: What do you mean by superconductivity? Discuss high temperature superconductors and some potential applications. (2022-23) View

Question: Discuss the effect of external magnetic field on superconductors. 

The transition temperature for Pb is 7.2K, however, at 5K it loses the superconducting property subjected to a magnetic field of 3.3 x 10^4 A/m. Find the maximum value of H which allow the metal to retain its superconductivity at 0 Kelvin. (2022-23) View

Question: Explain Type 1 and Type 2 superconductors briefly. (2022-23)

Question: Explain the Meissner effect and persistent current in superconductivity. (2022-23) View

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Nano materials 

Question: Discuss properties and the potential applications of nano materials. What are the risks of using nano materials to human body? (2022-23)

Question: Write down any two applications of the nano materials. (2022-23)

Question: What are Nano materials? Explain briefly the basic concepts of Quantum Dots, Quantum wires and Quantum wire and Quantum well. (2022-23)

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Fraunhofer diffraction at single slit

Question: Discuss the phenomena of Fraunhofer diffraction at  a single slit and show that the relative intensities of the successive maximum are nearly 1:4/9π² : 4/25π² : 4/49π²: ..... (2021-22)

Question: What do you understand by the phenomenon of Fraunhofer diffraction. Find out the ratio of intensities of successive secondary maxima compared to the intensity of the principle maximum. (2022-23)

Question: Discuss the phenomena of Fraunhofer diffraction at  a single slit and show that the relative intensities of the successive maximum are nearly 1:4/9π² : 4/25π² : 4/49π²: ....  (2020-21)

Question: Discuss the phenomenon of Fraunhofer diffraction at a single slit.Show that the intensity of the first subsidiary maximum is about 4.5% of the principal maximum. (2019-20)

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Some additional question

Question: A light of wavelength 6000Å falls normally on a slit of width 0.10mm. Calculate the total angular width of the central maximum. (2022-23)

Question: A 100 watt sodium lamp radiating its power. Calculate the electric field and magnetic field strength at a distance of 5m from lamp. (2020-21)

To be continued....