Physics Paper I - IFS Main 2019 (DFG-P-PHY)

Central Government Jobs Other Jobs 2019

  • Year 2019
  • Conducted By Not specified in OCR
  • Questions 8
  • Maximum Marks 200
  • Duration Three Hours Maximum Marks: 200
  • Languages English

Exam Details

Detail Information
Examination Indian Forest Service Exam (Main) - Physics Paper I
Year 2019
Conducting Body Not specified in OCR
Paper Physics Paper - I
Subject Physics
Duration Three Hours Maximum Marks: 200
Maximum Marks 200
Number of Questions 8
Question Type Mixed (mcq and descriptive)

This dataset covers Physics Paper I from the Indian Forest Service (IFS) Main Examination, 2019. Page 1 provides the exam header, time allowance, maximum marks, and explicit instructions for candidates, including the requirement to answer in English and the provision of useful physical constants. Page 2 presents Section A questions (Q1 and Q2) with multi-part prompts spanning rotational dynamics, laser physics (population inversion and wavelength determination), refractive index measurement via Newton's rings, cosmological Doppler-like shifts for moving galaxies, and the damping-related quality factor Q. The repair process yields corrected OCR structure, enabling precise extraction of the question stems for indexing and SEO. The questions emphasize both analytical reasoning and problem-solving across classical mechanics, optics, and quantum-related concepts relevant to physics at the level of the IFS Main examination.

Major Topics Covered

  • Indian Forest Service
  • Physics
  • Main Exam
  • Section A
  • Section B
  • Rotational Dynamics
  • Lagrangian Mechanics
  • Damped Harmonic Motion
  • Quality Factor
  • Newton's Rings
  • Refractive Index
  • Laser Physics
  • Population Inversion
  • Doppler Effect / Redshift
  • Energy Levels
  • Planck's Constant
  • Photon Energy
  • Wavelength Calculation
  • Energy Conservation
  • Classical Mechanics

Why This Paper is Important

  • Useful for Indian Forest Service Exam (Main) - Phys preparation
  • Helps understand the latest exam pattern
  • Useful for practice and self-assessment
  • Covers frequently asked General Studies topics
  • Helpful for analysing question trends

Related Resources

Instructions

  • There are EIGHT questions in all, out of which FIVE are to be attempted.
  • Out of the remaining SIX questions, THREE are to be attempted selecting at least ONE question from each of the two Sections A and B.
  • Attempts of questions shall be counted in sequential order.
  • Unless struck off, attempt of a question shall be counted even if attempted partly.
  • Any page or portion of the page left blank in the Question-cum-Answer Booklet must be clearly struck off.
  • The number of marks carried by a question/part is indicated against it.
  • Unless otherwise mentioned, symbols and notations have their usual standard meanings.
  • Assume suitable data, if necessary and indicate the same clearly.
  • Neat sketches may be drawn, wherever required.
  • Answers must be written in ENGLISH only.
  • Useful Constants: Electron charge (e) =
  • 602 \times 10^{-19} C =
  • 109 \times 10^{-31} kg Electron rest mass (m_e) Proton mass (m_p) =
  • 672 \times 10^{-27} kg Vacuum permittivity (\varepsilon_0) =
  • 854 \times 10^{-12} farad/m =
  • 257 \times 10^{-6} henry/m Vacuum permeability (\mu_0) Velocity of light in free space (c) = 3 \times 10^8 m/s Boltzmann constant (k) =
  • 380 \times 10^{-23} J/K Electron volt (eV) =
  • 602 \times 10^{-19} J =
  • 626 \times 10^{-34} Js Planck's constant (h) =
  • 67 \times 10^{-8} Wm-2 K-4 Stefan's constant (\sigma) Avogadro number (N) =
  • 022 \times 10^{26} kmol-1 =
  • 31 \times 10^3 J kmol-1 K-1 Gas constant (R) \exp(1) = 2.

Questions (page 2)

Q1.

(a) Q1. A mouse of mass m jumps on the outside edge of a freely turning ceiling fan of rotational inertia I and radius R. By what ratio does the angular velocity change? By what ratio does the angular velocity change?

(b) In a He-Ne laser system, the two energy levels of Ne involved in lasing action have energy values of 20.66 eV and 18.70 eV respectively. Population inversion occurs between these two energy levels. What will be the wavelength of the laser beam produced?

(c) What will be the population in the metastable energy level with respect to the upper excited level at room temperature (27°C)?

(d) How can the refractive index of a liquid be determined using a method of Newton's rings? Obtain an appropriate expression for calculating the refractive index.

(e) How fast and in what direction must galaxy A be moving if an absorption line found at wavelength 550 nm (green) for a stationary galaxy is shifted to 450 nm for galaxy A and how fast and in what direction is galaxy B moving if the same line is shifted to 700 nm for it?
(f) The quality factor Q in a damped harmonic motion is defined as Q = (2π × Average energy stored per cycle) / (Average energy dissipated per cycle). Show that Q = ω/(2h).

Q2. Q2. (a) An inclination angle θ at a constant rate α (θ = 0 at t = 0), causing the particle to move down the plane, as shown in the figure below. Write down the Lagrangian and determine the equations of motion. Solve the resulting equation for r to obtain the expression for r(t).

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Frequently asked questions

What is the full paper name and year?

Physics Paper I, Indian Forest Service Main Examination 2019.

How many questions must be attempted?

Eight questions in total; five are to be attempted.

Which questions are compulsory?

Questions 1 and 5 are compulsory.

From how many sections should questions be chosen?

From Sections A and B; at least one question from each section must be attempted.

In what language must answers be written?

Answers must be written in English.

Are constants provided in the paper?

Yes, useful constants are provided on the paper.

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