annaunivqp
2
http://jagadeeshinfotech2all.blogspot.com/2009/06/anna-university-random-number- enquiry.html http://www.mycrickethighlights.com/india-vs-new-zealand-2nd-test-day-5-highlights-2010- hyderabad/ B.E./B.Tech. DEGR EE EXAMINATION Third Semester El ectrical and Electr onics Engineering EC 253 — ELECTRON DEVICES Time : Three hours Maximum : 100 marks Answer ALL questions.PART A — (10 ? 2 = 20 marks) 1. An electron is injected perpendicularly into a uniform magnetic field of flux density 0.01 Wb/m2 with an initial speed of 107 m/s. What will be the radius of the circular path that the electron describes? 2. An ideal Germanium diode has a reverse saturatio n current of 20 ? A. Find the dynamic resistanc e for a forward bias of 0.1 V. 3. What is Hall effect? Give any two applications. 4. What are hybrid parameters? 5. Define diffusion current. 6. Give any two ways by which the transistors are protected from overheating due to high power operation. 7. What are the advantages of FETs? 8. Mention any two application s of SCR. 9. What is an optoelectronic coupler ? 10. Draw the basic structure of a CRT. PART B — (5 ? 16 = 80 marks) 11. (i) Explain about magnetic deflection in a CRT. Derive the expression for deflection sensitivity. (10) D 033 2 D 033 (ii) Find the speed of an electron after it has moved through a potential difference of 10,000 V. What would be the percentage change in its mass at this speed? (6) 12. (a) (i) Explain the origin of depletion layer capacitance and diffusion capacitance and discuss the importance of each. (8) (ii) What is a Schottky diode? What is its application? (8) Or (b) (i) You are given two different Ge diodes with their data at forward bias as follows : VD(on)1 = 0.7 V at 10 mA VD(on)2 = 0.6 V at 0.1 mA. If these diodes are placed in a series circuit and a current of 1 mA is made to flow in them (forward bias), what will be the sum of voltage drops across them? (8) (ii) Explain with relevant diagrams, the function of a Zener diode. Mention its important applications. (8) 13. (a) (i) Draw the hybrid ? model of a transistor in CE configuration and discuss about each component of the model. (10) (ii) Draw the Ebers–Moll model for a pnp transistor . (6)Or (b) (i) With appropriate diagrams, discuss about various switching times of a transisto r. (8) (ii) Compare the three configurations of a transistor. (8) 14. (a) Explain the function of depletion type MOSFET. Or (b) (i) Describe the operation of UJT. What is its main application? (10) (ii) Draw the low frequency small signal JFET model. (6) 15. (a) With neat sketches, discus s about the basic constructio n and operation of a laser diode. Name the different types of lasers. Or (b) What is a photo diode? With proper characteristi c curves and relevant diagrams, explain the operation of the
Transcript of annaunivqp
8/8/2019 annaunivqp
http://slidepdf.com/reader/full/annaunivqp 1/2
http://jagadeeshinfotech2all.blogspot.com/2009/06/anna-university-random-number-
enquiry.html
http://www.mycrickethighlights.com/india-vs-new-zealand-2nd-test-day-5-highlights-2010-hyderabad/
B.E./B.Tech. DEGREE EXAMINATION Third Semester Electrical and ElectronicsEngineeringEC 253 — ELECTRON DEVICES Time : Three hours Maximum : 100 marksAnswer ALL questions.PART A — (10 ? 2 = 20 marks)1. An electron is injected perpendicularly into a uniform magnetic field of fluxdensity 0.01 Wb/m2 with an initial speed of 107 m/s. What will be the radius of thecircular path that the electron describes?2. An ideal Germanium diode has a reverse saturation current of 20 ? A. Find thedynamic resistance for a forward bias of 0.1 V.3. What is Hall effect? Give any two applications.4. What are hybrid parameters?5. Define diffusion current.
6. Give any two ways by which the transistors are protected from overheating dueto high power operation.7. What are the advantages of FETs?8. Mention any two applications of SCR.9. What is an optoelectronic coupler?10. Draw the basic structure of a CRT.PART B — (5 ? 16 = 80 marks)11. (i) Explain about magnetic deflection in a CRT. Derive the expression fordeflection sensitivity. (10) D 033 2 D 033(ii) Find the speed of an electron after it has moved through a potential difference of 10,000 V. What would be the percentage change in its mass at this speed? (6)12. (a) (i) Explain the origin of depletion layer capacitance and diffusion capacitance
and discuss the importance of each. (8)(ii) What is a Schottky diode? What is its application? (8) Or(b) (i) You are given two different Ge diodes with their data at forward bias asfollows : VD(on)1 = 0.7 V at 10 mA VD(on)2 = 0.6 V at 0.1 mA. If these diodes areplaced in a series circuit and a current of 1 mA ismade to flow in them (forward bias), what will be the sum of voltage drops acrossthem? (8)(ii) Explain with relevant diagrams, the function of a Zener diode. Mention itsimportant applications. (8)13. (a) (i) Draw the hybrid ? model of a transistor in CE configuration and discussabout each component of the model. (10)(ii) Draw the Ebers–Moll model for a pnp transistor. (6)Or
(b) (i) With appropriate diagrams, discuss about various switching times of atransistor. (8)(ii) Compare the three configurations of a transistor. (8)14. (a) Explain the function of depletion type MOSFET. Or(b) (i) Describe the operation of UJT. What is its main application? (10)(ii) Draw the low frequency small signal JFET model. (6)15. (a) With neat sketches, discuss about the basic construction and operation of alaser diode. Name the different types of lasers. Or (b) What is a photo diode? Withproper characteristic curves and relevant diagrams, explain the operation of the
8/8/2019 annaunivqp
http://slidepdf.com/reader/full/annaunivqp 2/2
device. What are its applications?
