8 questions from the UPSC 2025 examination.
8 questions
Answer the following: Consider a uranium nucleus (₉₂U²³⁶) breaking up spontaneously into two equal parts. Estimate the reduction of electrostatic energy of the nucleus assuming a uniform charge distribution. [Assume the nuclear radius R = 1.2 × 10⁻¹³ A¹∕³ cm] [15M] Is it possible for a photon to transfer all its energy to a free electron? Give reasons. [5M] <!--qid:MAINS_2025_Physics-II_Q7-->
Answer the following: <!--qid:MAINS_2025_Physics-II_Q6-->
A reversible heat engine operates with three reservoirs at 300 K, 400 K and 1200 K. It absorbs 1200 kJ energy as heat from the reservoir at 1200 K and delivers 400 kJ work. Determine the heat interactions with the other two reservoirs. <!--qid:MAINS_2025_Physics-I_Q5-->
Answer the following five questions: <!--qid:MAINS_2025_Physics-II_Q1-->
Answer the following: From the pure rotational absorption spectra of a diatomic molecule (HF), the wave-number difference between consecutive rotational lines is Δν̄ = 4050 m⁻¹. Calculate (1) the rotational constant, (2) the moment of inertia, and (3) the bond length. [Given, M_H = 1 u, M_F = 19 u] [10M] The force constant of HCl molecule is 4.8 × 10⁵ dyne cm⁻¹. Calculate the wave numbers of Stokes and anti-Stokes lines when excited with radiation of wavelength 4358 Å. [Given, μ_HCl = 1.61 × 10⁻²⁴ g] [10M] <!--qid:MAINS_2025_Physics-II_Q3-->
Answer the following: What are the differences in the electrical characteristics of FET (JFET) and MOSFET? [7M] How does an n-channel FET differ from a p-channel FET? [3M] <!--qid:MAINS_2025_Physics-II_Q5-->
Answer the following: <!--qid:MAINS_2025_Physics-II_Q4-->
Answer the following: <!--qid:MAINS_2025_Physics-II_Q2-->