Edc objective question u i
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The document discusses diodes and other semiconductor devices. It contains 25 multiple choice questions about diode characteristics and applications. Specifically, it covers topics like diode testing, LED operation voltages and power ratings, rectifier output frequency, and the dominance of different capacitances in forward and reverse bias regions. The answers to the 25 questions are provided at the end.
Edc objective question u i
- 1. EC6202 ELECTRONIC DEVICES AND CIRCUITS Unit-I 1. The diode ________. (a) is the simplest of semiconductor devices (b) has characteristics that closely match those of a simple switch (c ) is a two-terminal device. (d) All of the above 2. What does a high resistance reading in both forward- and reverse-bias directions indicate? (a) A good diode. (b) An open diode. (c ) A shorted diode. (d) A defective ohmmeter. 3. Which capacitance dominates in the reverse-bias region? (a) depletion. (b) conversion. (c ) 40 Diffusion. (d) 140 None of the above. 4. In which of the following color(s) is (are) LEDs presently available? (a) Yellow. (b) White. (c) Orange. (d) All of the above. 5. Which of the following devices can check the condition of a semiconductor diode? (a) Digital display meter (DDM). (b) Multi meter. (c) Curve tracer. (d) All of the above. 6. In which of the following is the light intensity measured? (a) Candela (b) Efficacy (c ) Flux (d) Illumination 7. In general, LEDs operate at voltage levels from ________ V to ________ V. (a) 1.0, 3.0 (b) 1.7, 3.3 ( c ) 0.5, 4.0 (d) None of the above 8. What is the maximum power rating for LEDs? (a) 150 mW (b) 500 mW (c ) 1 W (d) 10 W 9. Which capacitance dominates in the forward-bias region? (a) Diffusion (b) Transition (c) Depletion (d) None of the above 10. Which of the following ratings is true? (a) Si diodes have higher PIV and narrower temperature ranges than Ge diodes. (b) Si diodes have higher PIV and wider temperature ranges than Ge diodes. (c) Si diodes have lower PIV and narrower temperature ranges than Ge diodes. (d) Si diodes have lower PIV and wider temperature ranges than Ge diodes. 11. The output frequency of a full-wave rectifier is ________ the input frequency. (a) one-half (b) equal to (c) twice (d) one-quarter 12. PIV is which of the following? (a) peak input voltage (b) peak inverse voltage
- 2. (c) peak immediate voltage (d) positive input voltage 13. What type of diode circuit is used to add or restore a dc level to an electrical signal? (a) clipper or limiter (b) clamper (c ) IC voltage regulator (d) none of the above 14. In general, LEDs operate at voltage levels from ________ V to ________ V. (a) 1.0, 3.0 (b) 1.7, 3.3 ( c ) 0.5, 4.0 (d) None of the above 15. In the operation of a half-wave rectifier with a capacitor-input filter, the ripple factor can be lowered by ________ the value of the filter capacitor or ________ the load resistors. (a) decreasing, decreasing (b) decreasing, increasing (c ) increasing, decreasing (d) increasing, increasing 16. Refer to this figure. Which symbol is correct for an LED? (a) a (b) b (c) c (d) d (e)e 17. The normal operating region for a zener diode is the (a) forward-bias region (b) reverse-bias region (c) zero-crossing region (d) reverse-breakdown region 18. Zener diodes with breakdown voltages greater than 5 V operate predominantly in what type of breakdown? (a) avalanche (b) zener ( c ) varactor (d) Schottky 19. The wide end arrow on a schematic indicates the ________ of a diode. (a) ground (b) direction of electron flow ( c ) cathode (d) anode 20. An n-type semiconductor material. (a) is intrinsic (b) has trivalent impurity atoms added ( c ) has pentavalent impurity atoms added (d) requires no doping. 21. Which statement best describes an insulator? (a) A material with many free electrons. (b) A material doped to have some free electrons ( c ) A material with few free electrons (d) No description fits. 22. The peak inverse voltage (PIV) across a non conducting diode in a bridge rectifier equals
- 3. approximately (a) half the peak secondary voltage (b) twice the peak secondary voltage (c)the peak value of the secondary voltage (d) four times the peak value of the secondary voltage 23. Electrons in the outermost orbit or shell of an atom are called (a) free electrons (b) negative ions (c) valence electrons (d) conduction band electrons 23. Shunting the ac component away from the load is the task of a (a) transformer (b) filter (c) regulator (d) rectifier 25. A pn junction allows current flow when (a) the p-type material is more positive than the n-type material (b) the n-type material is more positive than the p-type material (c) both the n-type and p-type materials have the same potential (d) there is no potential on the n-type or p-type materials Answers 1.d 2.b 3. a 4. d 5. d 6. a 7. b 8.a 9.a 10. b 11. c 12. b 13. b 14.b 15.d 16. a 17. d 18. a 19.d 20. c 21.c 22. c 23. c 24.b 25. a