GAS Lighter working principle

நாம் பொதுவாக நம் சமையலறையில் எல்பிஜி எரிவாயு பர்னர் எரிக்க தீ தூண்டி கருவி (Lighter) என்ற ஒரு இலகுவான கருவி உபயோகிறோம். தீ தூண்டி கருவி பின் பக்கம் ஒரு பொத்தானை தீப்பொறி உருவாக்க பெருவிரலால் அழுத்தும் போது தீப்பொறி உருவாகும் , அது எப்படி ?

தீ தூண்டி கருவி என்பது இப்போது எந்த சமையலறையிலும் மிக முக்கியமான கருவியாக உள்ளது. அது மின்சார அழுத்த விளைவு (Piezoelectric effect) என்ற கொள்கையின் அடிப்படையில் செயல்படுகிறது. இந்த தீ துண்டி கருவியில் குவார்ட்ஸ்(Quartz) படிகக்கல்(Crystals)  உள்ளது. இது இயல்பாகவே மிகவும் நல்ல முறையில்  மின்சார அழுத்த விளைவு உற்பத்தி செய்ய வல்லது. எனவே நாம் தீ தூண்டி கருவியின் பின்புறம் உள்ள பொத்தானை அழுத்தி விசை பயன்படுத்தும் போது குவார்ட்ஸ் படிகம் அங்கு ஒரு மின்னழுத்தை அதன் குறுக்கு திசையில் முழுவதும் உருவாகிறது. இது இங்கு ஒரு தீப்பொறி உருவாகிறது மேலும் இதனை கொண்டு எளிதில் எரியக்கூடிய எல்பிஜி என்ற வாயுவை மிகவும் எளிதில் பற்றக்கூடியதாக செய்துவிடுகிறது

GENRAL MODEL PAPER FOR CSIR NET EXAMINATION

GENERAL SCIENCES

MODEL QUESTION PAPER

PART A
ANSWER ANY 15 QUESTONS

1. Profit of a firm grows at a rate of 15% per year for the first three consecutive years. For the next three years, the profit level remains stagnant. From the 6th year till the 9th year, it again grows at a rate of 15% per year. Which of the following graphs depicts these facts?


2. A pond is deepest at its centre and becomes shallow uniformly towards the edge. If the depth of water at the centre in May is half its value in August, the water contained in the pond
(1) in May is greater than half that in August
(2) in August is equal to twice that in May
(3) in May is less than half that in August
(4) in August is less than twice that in May
3. The series representing the sum of the areas of the shaded equilateral triangles in
the figure below is
1. 3+2+1+1
2. 2 3 4
1 1 1 1
3 3 3 3
   
3. 2 3 4
1 1 1 1
4 4 4 4
   
4.
1 1 1 1
4 8 16 32
   
4. Which of the following vitamins will not be synthesized in a person confined to a
dark cell for a long time ?
1. A
2. B
3. C
4. D
5. Flowering is some plants is strongly influenced by the photo period. A farmer
was growing two species of plants, A and B near a sea coast where a light house
was located. He observed that species A flowered profusely while species B did
not. Which of the following is correct ?
1. Species A requires long duration of day while species B needs a shorter
day
2. Species B requires longer duration of day while species A needs a shorter
duration
3. Both species require short duration of day
4. Both species require long duration of day
6. Pneumatophores are modified roots in some plants like Rhizophora growing in swampy areas that come out of the ground and grow vertically upwards. The main function of such roots is to
(1) help obtain oxygen for respiration
(2) provide support
(3) adsorb and conduct water and minerals
(4) store food
7. A cube of side 1 cm is painted by putting a lacquer of thickness δ, negligible compared to the side of the cube. The volume of the painted cube is approximately
(1) 1 + δ cm3
(2) 1 + δ3 cm3
(3) 1 + 3δ3 cm3
(4) 1 + 3δ cm3
8. A candle is burning inside a sealed glass jar. The pressure and temperature of the air within the jar are plotted as a function of time. Which of the following graphs represents this process correctly?
9. The result of taking 1’s complement of the sum of the binary numbers 110 and 101 will be
(1) 1011
(2) 0011
(3) 0100
(4) 0110
10. Which of the following straight lines passes through the point (1,1)?
(1) y = 2x + 3
(2) 2y = x−6
(3) x = 1
(4) x = y + 1
11. Which of the following 1 molar (aqueous) solution has the highest number density of ions?
(1) Glucose
(2) CaCl2
(3) NaNO3
(4) KCl
12. How many two-digit even numbers can be composed from nine digits 1, 2, 3 … 9?
(1) 50
(2) 81
(3) 45
(4) 36
13. Complete combustion of cyclohexane (C6H12) is represented by the equation
C6H12 + x O2 → y CO2 + z H2O
The values of x, y and z, respectively, are
(1) 9, 6, 6
(2) 10, 6, 4
(3) 6, 12, 10
(4) 4, 8, 12
14. How many distinct trichlorobenzenes (C6H3Cl3) should exist, given that benzene (C6H6) has a regular hexagonal geometry?
(1) 6
(2) 1
(3) 2
(4) 3
15. Mercury is closer to the Sun than Venus. Yet Venus is hotter because it has
(1) a dominant CO2 atmosphere
(2) a dominant methane atmosphere
(3) sulphuric acid clouds
(4) an atmosphere devoid of oxygen
16. In a simple pendulum experiment, a student records the following readings. If the true period of the pendulum is 10 s, then the percent error is the largest for the observation with serial number
Serial Number
Number of Oscillations
Time
1
2
3
4
10
20
50
100
100.2
200.3
500.5
1000.8
(1) 1
(2) 2
(3) 3
(4) 4
17. A container holding normal air (1 bar pressure, room temperature) is being evacuated. The normal composition of air is approximately 78% N2, 21% O2, 0.9% Ar and traces of CO2 (0.04%) and water vapour (0.02%). After the pressure in the container falls to about 10–3 mbar, the relative fractions of the components will be
1. N2 and O2 approximately equal and greater than H2O
2. N2, O2, Ar approximately equal and greater than H2O
3. N2, O2, Ar in the original proportion, but N2 less than H2O
4. N2, O2, Ar in the original proportion, and N2 greater than H2O
18. An endoscope is a device for observing internal organs, using a combination of a lamp and an optical fibre. The image seen is due to
(1) light reflected by the organ and transmitted by internal reflection through the fibre
(2) light refracted by the organ and transmitted by refraction through the fibre.
(3) light refracted by the organ and transmitted by internal reflection through the fibre.
(4) light emitted by the organ and transmitted by refraction through the fibre.
19. How many times in a day is the angle between the minute and hour hands of a clock equal to an angle θ, where 00 < θ < 1800
(1) 24
(2) 12
(3) 36
(4) 48
20. A typical enzyme catalyzed reaction is shown below
What do you think the component x might be?
1. Substrate concentration or temperature
2. Substrate concentration or enzyme concentration
3. Substrate concentration or pH
4. pH or temperature

CSIR-UGC National Eligibility Test (NET) for Junior Research Fellowship and Lecturer-ship-Physical Sciences Syllabus

PART ‘A’ CORE

I. Mathematical Methods of Physics

Dimensional analysis. Vector algebra and vector calculus. Linear algebra, matrices, Cayley-Hamilton Theorem. Eigenvalues and eigenvectors. Linear ordinary differential equations of first & second order, Special functions (Hermite, Bessel, Laguerre and Legendre functions). Fourier series, Fourier and Laplace transforms. Elements of complex analysis, analytic functions; Taylor & Laurent series; poles, residues and evaluation of integrals. Elementary probability theory, random variables, binomial, Poisson and normal distributions. Central limit theorem.

II. Classical Mechanics

Newton’s laws. Dynamical systems, Phase space dynamics, stability analysis. Central force motions. Two body Collisions - scattering in laboratory and Centre of mass frames. Rigid body dynamics- moment of inertia tensor. Non-inertial frames and pseudoforces. Variational principle. Generalized coordinates. Lagrangian and Hamiltonian formalism and equations of motion. Conservation laws and cyclic coordinates. Periodic motion: small oscillations, normal modes. Special theory of relativity- Lorentz transformations, relativistic kinematics and mass–energy equivalence.
III. Electromagnetic Theory
Electrostatics: Gauss’s law and its applications, Laplace and Poisson equations, boundary value problems. Magnetostatics: Biot-Savart law, Ampere's theorem. Electromagnetic induction. Maxwell's equations in free space and linear isotropic media; boundary conditions on the fields at interfaces. Scalar and vector potentials, gauge invariance. Electromagnetic waves in free space. Dielectrics and conductors. Reflection and refraction, polarization, Fresnel’s law, interference, coherence, and diffraction. Dynamics of charged particles in static and uniform electromagnetic fields.

IV. Quantum Mechanics

Wave-particle duality. Schrödinger equation (time-dependent and time-independent). Eigenvalue problems (particle in a box, harmonic oscillator, etc.). Tunneling through a barrier. Wave-function in coordinate and momentum representations. Commutators and Heisenberg uncertainty principle. Dirac notation for state vectors. Motion in a central potential: orbital angular momentum, angular momentum algebra, spin, addition of angular momenta; Hydrogen atom. Stern-Gerlach experiment. Time-independent perturbation theory and applications. Variational method. Time dependent perturbation theory and Fermi's golden rule, selection rules. Identical particles, Pauli exclusion principle, spin-statistics connection.

V. Thermodynamic and Statistical Physics

Laws of thermodynamics and their consequences. Thermodynamic potentials, Maxwell relations, chemical potential, phase equilibria. Phase space, micro- and macro-states. Micro-canonical, canonical and grand-canonical ensembles and partition functions. Free energy and its connection with thermodynamic quantities. Classical and quantum statistics. Ideal Bose and Fermi gases. Principle of detailed balance. Blackbody radiation and Planck's distribution law.

VI. Electronics and Experimental Methods

Semiconductor devices (diodes, junctions, transistors, field effect devices, homo- and hetero-junction devices), device structure, device characteristics, frequency dependence and applications. Opto-electronic devices (solar cells, photo-detectors, LEDs). Operational amplifiers and their applications. Digital techniques and applications (registers, counters, comparators and similar circuits). A/D and D/A converters. Microprocessor and microcontroller basics.Data interpretation and analysis. Precision and accuracy. Error analysis, propagation of errors. Least squares fitting,

PART ‘B’ ADVANCED

I. Mathematical Methods of Physics

Green’s function. Partial differential equations (Laplace, wave and heat equations in two and three dimensions). Elements of computational techniques: root of functions, interpolation, extrapolation, integration by trapezoid and Simpson’s rule, Solution of first order differential equation using Runge-Kutta method. Finite difference methods. Tensors. Introductory group theory: SU(2), O(3).

II. Classical Mechanics
Dynamical systems, Phase space dynamics, stability analysis. Poisson brackets and canonical transformations. Symmetry, invariance and Noether’s theorem. Hamilton-Jacobi theory.
III. Electromagnetic Theory
Dispersion relations in plasma. Lorentz invariance of Maxwell’s equation. Transmission lines and wave guides. Radiation- from moving charges and dipoles and retarded potentials.
IV. Quantum Mechanics
Spin-orbit coupling, fine structure. WKB approximation. Elementary theory of scattering: phase shifts, partial waves, Born approximation. Relativistic quantum mechanics: Klein-Gordon and Dirac equations. Semi-classical theory of radiation.
V. Thermodynamic and Statistical Physics
First- and second-order phase transitions. Diamagnetism, paramagnetism, and ferromagnetism. Ising model. Bose-Einstein condensation. Diffusion equation. Random walk and Brownian motion. Introduction to nonequilibrium processes.
VI. Electronics and Experimental Methods
Linear and nonlinear curve fitting, chi-square test. Transducers (temperature, pressure/vacuum, magnetic fields, vibration, optical, and particle detectors). Measurement and control. Signal conditioning and recovery. Impedance matching, amplification (Op-amp based, instrumentation amp, feedback), filtering and noise reduction, shielding and grounding. Fourier transforms, lock-in detector, box-car integrator, modulation techniques.High frequency devices (including generators and detectors).
VII. Atomic & Molecular Physics
Quantum states of an electron in an atom. Electron spin. Spectrum of helium and alkali atom. Relativistic corrections for energy levels of hydrogen atom, hyperfine structure and isotopic shift, width of spectrum lines, LS & JJ couplings. Zeeman, Paschen-Bach & Stark effects. Electron spin resonance. Nuclear magnetic resonance, chemical shift. Frank-Condon principle. Born-Oppenheimer approximation. Electronic, rotational, vibrational and Raman spectra of diatomic molecules, selection rules. Lasers: spontaneous and stimulated emission, Einstein A & B coefficients. Optical pumping, population inversion, rate equation. Modes of resonators and coherence length.
VIII. Condensed Matter Physics
Bravais lattices. Reciprocal lattice. Diffraction and the structure factor. Bonding of solids. Elastic properties, phonons, lattice specific heat. Free electron theory and electronic specific heat. Response and relaxation phenomena. Drude model of electrical and thermal conductivity. Hall effect and thermoelectric power. Electron motion in a periodic potential, band theory of solids: metals, insulators and semiconductors. Superconductivity: type-I and type-II superconductors. Josephson junctions. Superfluidity. Defects and dislocations. Ordered phases of matter: translational and orientational order, kinds of liquid crystalline order. Quasi crystals.
IX. Nuclear and Particle Physics
Basic nuclear properties: size, shape and charge distribution, spin and parity. Binding energy, semi-empirical mass formula, liquid drop model. Nature of the nuclear force, form of nucleon-nucleon potential, charge-independence and charge-symmetry of nuclear forces. Deuteron problem. Evidence of shell structure, single-particle shell model, its validity and limitations. Rotational spectra. Elementary ideas of alpha, beta and gamma decays and their selection rules. Fission and fusion. Nuclear reactions, reaction mechanism, compound nuclei and direct reactions.Classification of fundamental forces. Elementary particles and their quantum numbers (charge, spin, parity, isospin, strangeness, etc.). Gellmann-Nishijima formula. Quark model, baryons and mesons. C, P, and T invariance. Application of symmetry arguments to particle reactions. Parity non-conservation in weak interaction. Relativistic kinematics.