UNIT BASED ONLINE EXTERNAL EXAMINATION - OCTOBER – 2020 - OPTICS AND SPECTROSCOPY - 7BPH3C1

 CLICK HERE TO DOWNLOAD THE QUESTION AS A PDF

ALAGAPPA UNIVERSITY
KARAIKUDI – 630 003
UNIT BASED ONLINE EXTERNAL EXAMINATION - OCTOBER – 2020

THIRD SEMESTER SLOT – I

OPTICS AND SPECTROSCOPY 7BPH3C1

DATE: 29.10.2020

Total Marks: 50                                                                                            Time: 2.0 Hrs

SECTION A - MCQ - 20 x 1 = 20 Marks

1. A biconcave lens consists of

A. Two concave faces in opposite directions                     B. Two concave faces in the same direction

C. A concave and a convex face in opposite directions     D. Two convex faces in opposite directions

2. Marginal rays are

A. Rays close to the principal axis                              B. Rays close to the edge of the lens

C. Rays along the principal axis                                  D. Rays through the center of the lens          

3. For reducing spherical aberration using a combination of lenses, the criterion is,

A. d = f₁ x f₂                                                                 B. d = f₁ / f₂

C. d = f₁ - f₂                                                                  D. d = f₁  ̴ f₂

Where f₁ and f₂ are the focal lengths of the lenses and d is the separation between them.

4. Chromatic aberration in lenses is due to the phenomenon of

A. Dispersion                                                               B. Reflection

C. Interference                                                             D. Diffraction

5. Which of the following telescope design greatly reduces the chromatic aberration in image formation?

A. Galilean                                                                  B. Keplerian

C. Newtonian                                                              D. Copyscope 

6. Coma is called so since,

A. It’s an acronym                                                       B. The image formed looks like a comet

C. It looks like coma                                                    D. It’s senseless  

        

7. Dispersion of waves depends on

A. their amplitude                                                      B. their wavelength

C. their speed                                                             D. All of these three                                                   

8. Dispersion in a medium arises due to the interaction of light waves with

A. the electrons                                                          B. the ions

C. the neutrons                                                           D. the protons

9. The use of Canada balsam as a cement in optical instruments is because

A. it’s very hard                                                                                      B. it’s opaque

C. it’s transparent and has nearly same refractive index as glass    D. it’s very soft    

       

10. A use of direct vision spectroscope is

A. Measuring the temperature                                  B. Analyzing the quality of gems

C. Evaluating pressure                                              D. Measuring colors  

11. Primary rainbow is formed due to

A. a single internal reflection                                     B. two internal reflections

C. three internal reflections                                       D. none of the others 

12. Secondary rainbow’s color order is

A. same as that of the primary rainbow                    B. inverted to that of the primary rainbow

C. green, red, orange and blue                                  D. red, yellow, blue and orange                                

13. Condition[s] for sustained interference between light waves

A. Sources must be coherent                             B. Sources must be narrow (of the order of the wavelength)

C. Sources must emit light of same frequency D. All the other options

14. In the condition for constructive interference is [Stoke’s rule applicable], the path difference must be

A. Integral multiples of wavelength                           B. Fractional multiples of wavelength

C. Half odd integral multiples of wavelength            D. A single wavelength       

   

15. The vibrant colors of the peacock feathers is due to

A. polarization                                                             B. absorption

C. refraction                                                                D. interference          

16. A primary application of air wedge is

A. measurement of intensity                                      B. measurement diameter of a thin wire

C. measurement of chromaticity                               D. None of the others

17. The interference fringe width pattern of a surface against an optical is directly related to

A. Area of the surface                                                 B. Topography of the surface

C. Volume of the surface                                            D. Global slope of the surface                                                           

18. The radii of rings in Newton rings is directly proportional to

A. square of integers                                                     B. reciprocal of integers

C. reciprocal of square root of natural numbers        D. square root of natural numbers

19. A recent application of Michelson Interferometer which earned a Nobel Prize is,

A. Observation of Gravitational Waves                      B. Discovery of Blue LED

C. Birth and Death of Stars                                         D. Discovery of Laser 

20. The compensator in Jamin’s interferometer is used for

A. counting the number of fringes manually   B. measuring the wavelength of light

C. measuring the pressure of the gas              D. conveniently measuring the refractive index directly           

 

SECTION B - DESCRIPTIVE - 5 x 6 = 30 Marks

ANSWER ANY FIVE

21. Derive the condition for minimization of spherical aberration when two thin lenses are separated by a distance.

22. Explain the working of Huygens eyepiece.

23. Explain the construction and working of a direct vision spectroscope.

24. Discuss how an aplanatic lens eliminates spherical aberration.

25. Discuss the theory of formation of secondary rainbow.

26. Describe the effect of interference in reflected light from thin films.

27. Discuss the theory of air wedge with neat diagrams.

28. Derive the expression for the radii of the rings formed in Newton rings experiment.

UNIT BASED ONLINE EXTERNAL EXAMINATION - OCTOBER – 2020 - ANALOG ELECTRONICS - 7BPH5C1

CLICK HERE TO DOWNLOAD THIS QUESTION AS A PDF.

 

ALAGAPPA UNIVERSITY
KARAIKUDI – 630 003
UNIT BASED ONLINE EXTERNAL EXAMINATION - OCTOBER – 2020
FIFTH SEMESTER SLOT – I

ANALOG ELECTRONICS 7BPH5C1

Total Marks: 50                                                                                           Time: 2.0 Hrs

SECTION A - MCQ - 20 x 1 = 20 Marks

1. To turn an intrinsic semiconductor into a p-type extrinsic semiconductor which one of the following materials can be mixed with it?

A. Silicon                                                                     B. Diamond

C. Phosphorous                                                           D. Boron         

2. The forward resistance of a diode has the following order of magnitude value

A. 10³ Ω                                                                       B. 10⁶ Ω

C. 10 Ω                                                                         D. 10⁵ Ω                                                          

3. The forward voltage drop of a silicon diode is around

A. 5 V                                                                          B. 7 V

C. 0.7 V                                                                        D. 100 V

4. What is the special property of a diode, which makes it very useful?

A. Conduction in both directions                                B. Conduction in the forward direction only

C. Its high resistance                                                     D. Zero resistance      

5. The diode is /a/an

A. Linear device                                                          B. Android device

C.  None of the other three choices                            D. Non-linear device  

6. The main application of a Zener diode is

A. Amplification                                                          B. Rectification

C. Voltage regulation                                                  D. Voltage multiplication       

7. The main disadvantage of a half wave rectifier is

A. It uses only one diode                                             B. Ripple factor is high

C. Requirement of diode with high power rating    D. It’s too simple

8. The maximum theoretical efficiency of a full wave rectifier is

A. 80.2 %                                                                     B. 81.2 %

C. 40.6 %                                                                     D. 33.3 %

9. Ripple factor of a half wave rectifier is

A. 1.21                                                                         B. 3.14

C. 2.12                                                                         D. 5.34

10. A capacitor blocks

A. AC                                                                           B. DC

C. Voltage                                                                    D. Current

11. BJT stands for

A. Bi Junction Tetrode                                                            B.  By Jitter Triode

C. Bipolar Junction Transistor                                              D. None of the others

12. The transistor transfers current flow from 

A. Low resistance side to high resistance side           B. Low resistance side to low resistance side

C. High resistance side to high resistance side          D. High resistance side to low resistance side

13. Number of PN junctions in a transistor is/are

A. 1                                                                              B. 2

C. 0                                                                              D. 4

14. The depletion region is devoid of

A. Ions                                                                        B.  Mobile charges

C. Protons                                                                  D. Neutrons

15. A BJT has following three parts

A. Emitter, Base and Collector                                    B.  Gate, Source and Drain

C. Anode, Cathode and Electrode                               D. Emitter, Drain and Gate

16. The Base-Emitter voltage drop is approximately [for silicon transistors]

A. 0.9 V                                                                       B. 1.2 V

C. 0.6 V                                                                       D. 3.4 V

17. The schematic symbol for a NPN transistor shows the emitter arrow

A. to come out                                                            B. to go in  

C. No arrow is drawn                                                D. to go in and out

18. The base of a PNP transistor is

A. a p-type extrinsic semiconductor                           B. intrinsic semiconductor 

C. a c-type semiconductor                                          D.  an n-type extrinsic semiconductor

19. Current gain (β) of a BJT [in CE mode] has a typical value of, around

A. 300                                                                          B. 10

C. 1000                                                                        D. 1

20. The base, emitter and collector currents in an NPN transistor obeys the equation

A. I_C = I_E + I_B                                                              B.  I_C = I_E - I_B  

C. I_B = I_E + I_C                                                               D. I_C = I_E + I_B  

SECTION B - DESCRIPTIVE - 5 x 6 = 30 Marks

ANSWER ANY FIVE

21. What are intrinsic and extrinsic semiconductors? How are they formed?

22. Describe the working of a bridge rectifier with neat circuit diagram.

23. Derive an expression for the efficiency of a half wave rectifier.

24. Explain the working of an RC filter. What are its’ disadvantages?

25. Explain the working of a Zener voltage regulator with neat diagrams.

26. Describe the characteristics of a transistor in CE mode.

27. Derive the relationship between α and β.

28. Explain the potential divider bias in detail.