Triangular Wave Generator Using Op-Amps

A triangular wave generator using op-amps can be realized by cascading the output of an op-amp square wave generator to the input of an active integrator. Such an implementation is shown in the following circuit diagram. 

Triangular Wave Generator

Working and Circuit Analysis

Here the first op-amp is wired up as a  comparator at the non-inverting input. If V+ is greater than V- then the output voltage V' will swing to +Vcc and to -Vcc if V+ is less than V- . When the circuit is switched on assume the output voltage is +Vcc and the capacitor C begins charging through the feedback resistor R with the time constant RC. As a result V-   increases with time and when it becomes greater than V+ the output voltage swings to the negative rail voltage -Vcc. Now the capacitor is is discharged through R. When the voltage becomes less than -Vcc the output voltage swings back to +Vcc and the cycle begins again generating square wave. 

The output of square wave generator V' is fed into the inverting input of second op-amp wired as an active integrator through the resistance R3  . 

A triangular wave is generated when a capacitor is charged and discharged by a constant current source. Let V' be hight at +Vcc. This causes a constant current +Vcc/R3 through C in the integrator part to drive Vout negative linearly. When V' is low at -Vcc it forces a constant current  -Vcc/R3  through  C to drive Vout positive linearly. The frequency of the triangular wave is same as that of square wave and given by, 

for the special case R1 =  R2.

ANALOG ELECTRONICS PRIOR UNIVERSITY QUESTIONS

Square Wave Generator Using Op-Amp

A square wave generator's output oscillates between two unstable states with a constant frequency prescribed by the circuit parameters. An op-amp implementation of square wave generator is shown in the following circuit diagram. 

Working and Circuit Analysis

Square Wave Generator Using Op-Amp

Here the op-amp is wired up as a  comparator at the non-inverting input. If V+ is greater than V- then the output voltage Vout will swing to +Vcc and to -Vcc if V+ is less than V- . When the circuit is switched on assume the output voltage is +Vcc and the capacitor C begins charging through the feedback resistor R with the time constant RC. As a result V-   increases with time and when it becomes greater than V+ the output voltage swings to the negative rail voltage -Vcc. Now the capacitor is is discharged through R. When the voltage becomes less than -Vcc the output voltage swings back to +Vcc and the cycle begins again generating square wave. The capacitor charging and discharging cycles and output waveforms are sketched below:

Square Wave Generator Waveforms

Voltage at the non-inverting input is  given by the divider equation:

As the output voltage swings between +Vcc  and -Vcc , V+  swings between 

and

If R1 and R2 are equal, the frequency of oscillation will be given by,

OPTICS AND SPECTROSCOPY PRIOR UNIVERSITY QUESTIONS

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OPTICS AND SPECTROSCOPY- 4BPH3C1 QUESTION BANK

OPTICS AND SPECTROSCOPY- 4BPH3C1

PART – A

1. Distinguish between Ramsden eyepiece and Huygens eyepiece.
2. Write short note on chromatic aberration in lenses.
3. Give three methods of minimizing spherical aberration.
4. Define dispersive power of a prism.
5. What is an achromatic doublet?
6. How chromatic aberration is minimized in the case of Huygens and Ramsden eyepieces.
7. Explain briefly about coma.
8. Explain the construction of Ramsden eyepiece with a suitable diagram.
9. Explain the construction of Huygens eyepiece with a suitable diagram.
10. What is an air wedge? State its uses.
11. Give the principle of Jamin interferometer.
12. State Stoke’s law.
13. Explain appearance of colors in thin films.
14. State the uses of Michelson interferometer.
15. Define resolving power .state Rayleigh criterion for resolution.
16. Define resolving power of a grating.
17. Define specific rotation or specific rotatory power.
18. What is a quarter wave plate?
19. What is a half wave plate?
20. What is the difference between unpolarized light and polarized light?
20. Write short notes on quarter wave plate.
21. Write short notes on half wave plate.
22. State and explain Malus law.
23. Write a note on FTIR.
24. Define Spectroscopy.
25. What is Anti-Stokes line?
26.Give the Application of vibrational Raman spectra.
27. What is a selection rule?
28.Expand FTIR.

PART – B

1. Derive the condition for minimization of spherical aberration when two thin lenses are separated        by a distance.
2. What is an achromatic doublet? Explain in detail.
3. Explain the working of Huygens eyepiece.
4. Write note on Ramsden eyepiece.
5. Explain the construction and working of a direct vision spectroscope.
6. Describe the effect of interference in reflected light from thin films.
7. Explain how colors appear in thin films due to interference.
8. Describe the experiment to find diameter of a thin wire by air wedge method.
9. Explain the principle and working of Jamin interferometer for determining the refractive index of        gas.
10. Explain how Jamin interferometer is used to study the refractive index of a gas at different                  pressures.
11. Distinguish between Fresnel diffraction and Fraunhofer diffraction.
12. Show that the radii of half period zones are in the ratio of square roots of natural numbers.
13. Explain Fresnel diffraction of light at a circular aperture.
14. Explain Fraunhofer diffraction of light at a single slit.
15. Discuss the Fraunhofer diffraction pattern due to a single slit.
16. Derive an expression for the resolving power of a grating.
17 .Give the Huygens explanation of double refraction in a uni-axial crystal.
18. Give the theory of half wave plate.
19. Give the theory of quarter wave plate.
20. Write note on Microwave and Raman spectroscopy.
21. Explain classical theory of Raman effect.
22. Explain vibrational Raman spectra.
23. Discuss Rotational spectra of diatomic molecules. Give its selection rule.
25. Explain Microwave and Infrared spectroscopy.
26. Explain pure rotational Raman spectrum of linear molecules.

PART – C

1. Define angular dispersion and dispersive power. Derive the conditions to produce (i) dispersion without deviation and (ii) deviation without dispersion in combination of prisms.
2. Derive the condition for achromatism in lenses (i) When they are in contact (ii) When they are separated by a distance ‘a’.
3. What is meant by spherical aberration in lenses?  What are the ways to remove spherical aberration?
4. Explain the construction, action and working of a Ramsden eyepiece and Huygens eye piece with neat diagrams. Indicate in a diagram the position of cardinal points for these two eyepieces. How are the chromatic and spherical aberration minimized in these eyepieces?
5. Describe with necessary theory the Newton’s ring experiment for the determination of refractive index of a liquid.
6. Explain the working of Michelson interferometer. How the wavelength of monochromatic light can be measured?
7. Derive the expression for the radius of m^th ring formed in Newton’s ring experiment and hence determine the refractive index of a liquid.
8. Describe Michelson interferometer and explain the formation of fringes in it. How was the instrument used for the standardization of meter?
9. Explain with theory how the wavelength of the light can be determined using diffraction grating by oblique incidence method.
10. Give the theory of plane transmission grating. Describe an experiment to determine the wavelength of sodium light.
11. Define specific rotation and explain Fresnel theory of optical rotation.
12. Describe Laurent’s half shade polarimeter and explain how specific rotary power is determined.
13. Explain the production and the analysis of circularly and elliptically polarized light.
14.   Explain how elliptically and circularly polarized light can be produced and analyzed.
15.   Explain the production and detection of plane, circularly and elliptically polarized light.
16.   Give the theory of production of circularly and elliptically polarized light.
17.   Explain Quantum theory of Raman effect.

Properties of Matter University Question Collection

Syllabus For Allied Physics Academic Year 2017-2018 Onwards

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Summation of Series in Fraunhofer Single Slit Theory

Question Bank for Solid State Physics Part - A

     Solid State Physics Question Bank

         Paper Code: 4BPHE2C

PART –A

Answer ALL the question ( No Choice)(Each answer not exceeding 50 wards in one or two sentences)

    (10 x 2 = 20 marks)

Unit – I
1. What is cohesive energy?
2. What are the classifications of cohesive force in crystal?
3. List out the different types of bonding with any two examples.
4. Define the Lattice energy
5. Obtain the dissociation energy.
6. What is ionization energy?
7. Define electron affinity.
8. Define Born Haber cycle.
9. Draw the structure of the hydrogen bond in water
10. Give the formula of electrostatic energy of an ionic crystal.
11. Define Madelung constant.
12. What holds a crystal together?
Unit - II
13. Distinguish between conductor and insulator.
14. Define Isotope effect.
15. Define Meissner effect.
16. What are these simplest way to understand the AC and DC Josephson effect?
17. What is Coherence length?
18. Write note on zero resistivity of a super conductor.
19. What is the meant by phonon cloud?
20. Give the modern theory of super conductivity.
21. How is the contribution of cooper pairs of electrons in the superconductor?
22. Write the BCS theory.
23. Write the idea of penetration depth
24. Write the central properties of superconductors.
Unit - III
25. Write note on physical properties of metals
26. Define polarization
27. Mention the various fields of dielectric parameters.
28. Write note on electrical conductivity of metals.
29. What is dielectric breakdown?
30. State  Weidmann – Franz’s law
31. What are the types of polarization?
32. Define the dielectric constant of an isotropic medium.
33. Define the polarizability of an atom.
34. List out the types of dielectric materials
35. Write down the Clausius – Mossotti equation
36. Give the applications of dielectric materials.
Unit – IV
37. List out the optical properties of semiconductors.
38. Give the types of semiconductors with example?
39. Distinguish between conductors, semiconductors and insulators.
40. Give the relations between carrier concentration and mobility of different semiconductors.
41. Find polarity of semiconductor through the sign of the Hall voltage.
42. Write a note on intrinsic semiconductors
43. Write a note on extrinsic impurity semiconductors with suitable examples
44. What is the Physical law manifested in the continuity equation?
45. Deduce Einstein relation
46. What is meant by conductivity in a semiconductor?
47. What is the value of the Hall coefficient? Assume no acceptor atoms are present and that   Eg ≫ k T.
48. Give  two important applications of Hall effect.
Unit – V
49. Give an application of photo diode.
50. Define Thermistors
51. What is the meant by avalanche photo diode?
52. Define the unit of photo conductivity.
53. Draw neat diagram of solar cell.
54. What is meant by Luminescence?
55. What is the physical significance of photo diode?
56. List out the semiconductor devices.
57. Distinguish between Photo conductivity and electrical conductivity.
58. Write the relation  between Photo conductive cell and solar cell
59. Define Photo Voltaic effect.
60. Give few semiconductor applications.