(a)Derive the work-energy theorem of electrodynamics (Poynting theorem) and discuss the Poynting vector. [10]
(b)What is magnetic vector potential? Also compare magnetic vector potential and electric scalar potential. [5]
(c)Find the magnetic field a distance z above the center of a circular loop of radius R, which carries a steady current I. [5]
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Q. 3
(a)What are the limitations of Gauss's Law? How it can be applied on a material with bound charges (dielectrics)? [10]
(b)The long solenoid has 220 turns/cm and carries a current i = 1.5 A; its diameter D is 3.2 cm. At its center we place a 130-turn closely packed coil C of diameter d = 2.1 cm. The current in the solenoid is reduced to zero at a steady rate in 25 ms. What is the magnitude of the emf that is induced in coil C while the current in the solenoid is changing? [5]
(c)Calculate the Curl of electric field E. [5]
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Q. 4
(a)Briefly discuss the phenomenon of Photoelectric effect. Deduce the value of Plank's constant using concepts of stopping potential and work function. [10]
(b)X rays of wavelength λ = 22 pm (photon energy = 56 keV) are scattered from a carbon target, and the scattered rays are detected at 85° to the incident beam. What is the Compton shift of the scattered rays? [5]
(c)Describe the significance of a nearby nucleus in the process of pair production. Why is it necessary for the phenomenon to take place? [5]
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Q. 5
(a)Explain the splitting of energy levels of atoms in external magnetic field based on the quantum theory by considering the spectral lines of sodium. [10]
(b)Discuss the momentum and energy operators in quantum mechanics and write down the significance of these operators. [5]
(c)Show that the particle in one dimensional box can only have discrete energy values. [5]
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Q. 6
(a)How the energy levels in the crystalline solids form the energy bands? Differentiate between metals and semiconductors based on the band gap pattern and electrical properties of the solids. [10]
(b)How many conduction electrons are in a cube of sodium ²³₁₁Na of volume 2 × 10⁻⁶ m³. Sodium atoms are monovalent. Density and molar mass of sodium are 0.968 g/cm³ and 22.98 g/mol respectively. [5]
(c)What is a Bravais lattice? Write down types of Bravais lattice in three-dimensional space. [5]
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Q. 7
(a)How radiations are detected? Discuss any two radiation detectors in detail. [10]
(b)Explain working principle of the cyclotrons and synchrotrons. [5]
(c)Suppose a cyclotron is operated at an oscillator frequency of 12 MHz and has a dee radius R = 53 cm. What is the magnitude of the magnetic field needed for deuterons to be accelerated in the cyclotron? The deuteron mass is m = 3.34 × 10⁻²⁷ kg (twice the proton mass). What is the resulting kinetic energy of the deuterons? [5]
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Q. 8
(a)Discuss the working principle and applications of MOSFET. [10]
(b)What is the probability that a quantum state whose energy is 0.10 eV above the Fermi energy will be occupied? Assume a sample temperature of 800 K. [5]
(c)Graphically show the occupancy probability and density of states as a function of energy. [5]
The 2024 CSS Physics paper set by the Federal Public Service Commission. Question wording only; questions marked “Not yet checked” have not been compared with the official paper yet. Open the official paper beside the questions to check any of them.
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