Download OU B.Sc 2019 June-July 2nd Semester 3040 Electronics Devices Question Paper

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FACULTY OF SCIENCE

B.Sc. II-Semester (CBCS) Examination, May / June 2019

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Subject : Electronics

Paper - II : Electronic Devices

Time : 3 Hours Max. Marks: 80

PART - A (5 x 4 = 20 Marks)

(Short Answer Type)

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Note : Answer any FIVE of the following questions.

1. Explain tunneling phenomenon.
2. Explain the junction capacitance.
3. Define a and ß of a transistor and derive the relation between them.
4. The collector current of a transistor is 5mA. If ß=140, I_B=35uA, then calculate leakage current I_CEO.

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5. Explain briefly UJT as relaxation oscillation.
6. An N-channel JFET has a pinch-off voltage of -4.5v and I_DSS = 9mA. At what value of V_GS in the pinch off region will I_D equal to 3mA?
7. Draw the diagram of LED and mention its applications.
8. Mention Application of SCR.

PART - B (4 x 15 = 60 Marks)

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(Essay Answer Type)

Note: Answer ALL the questions.

1. (a) How is P-N junction diode formed? Explain its characteristic curves and types of breakdowns.

   OR

   (b) Describe the construction and working of a varactor diode. Draw and explain its characteristics.
2. (a) Explain the two methods of transistor biasing.

   OR

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   (b) Define h-parameters for a low frequency CE transistor. Give an equivalent h-parameter model for a BJT under CE configuration.
3. (a) Explain the construction and working of UJT. Explain its characteristics.

   OR

   (b) Explain the construction and working of UJT. Explain its characteristics.
4. (a) Draw a half-wave SCR circuit and explain its operation. Indicate the current and voltage waveform of the SCR.

   OR

   (b) Explain the construction and operation of a photovoltaic cell. Mention its applications.

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