Semiconductor Diode MCQs Questions & Answers


In this post composed with  Electrical Interview Questions,Answers On Semiconductor Diode  MCQs Questions,Answers On  Semiconductor Diode which are asked in most of the interviews and competitive exams like GATE (India),PGCET..etc.

Electrical Interview Questions On Semiconductor Diode

1. A crystal diode has ........

(i) one pn junction
(ii) two pn junctions
(iii) three pn junctions
(iv) none of the above



2. A crystal diode has forward resistance of the order of ........

(i) kΩ
(ii) Ω
(iii) MΩ
(iv) none of the above



3. If the arrow of crystal diode symbol is positive w.r.t. bar, then diode is ........ biased.

(i) forward
(ii) reverse
(iii) either forward or reverse
(iv) none of the above



4. The reverse current in a diode is of the order of ........

(i) kA 
(ii) mA
(iii) μA 
(iv) A



5. The forward voltage drop across a silicon diode is about ........

(i) 2.5 V 
(ii) 3 V
(iii) 10 V 
(iv) 0.7 V



6. A crystal diode is used as ........

(i) an amplifier 
(ii) a rectifier
(iii) an oscillator 
(iv) a voltage regulator




7. The d.c. resistance of a crystal diode is ........ its a.c. resistance.


(i) the same as
(ii) more than
(iii) less than
(iv) none of the above





8. An ideal crystal diode is one which behaves as a perfect ........ when forward biased.



(i) conductor

(ii) insulator
(iii) resistance material
(iv) none of the above



9. The ratio of reverse resistance and forward resistance of a germanium crystal diode is about ........

(i) 1 : 1 
(ii) 100 : 1
(iii) 1000 : 1 
(iv) 40000 : 1



10. The leakage current in a crystal diode is due to ........

(i) minority carriers
(ii) majority carriers
(iii) junction capacitance
(iv) none of the above



11. If the temperature of a crystal diode increases,then leakage current ........

(i) remains the same
(ii) decreases
(iii) increases
(iv) becomes zero



12. The PIV rating of a crystal diode is ........ that of equivalent vacuum diode.

(i) the same as 
(ii) lower than
(iii) more than 
(iv) none of the above



13. If the doping level of a crystal diode is increased,the breakdown voltage .........

(i) remains the same
(ii) is increased
(iii) is decreased
(iv) none of the above



14. The knee voltage of a crystal diode is approximately equal to ........

(i) applied voltage
(ii) breakdown voltage
(iii) forward voltage
(iv) barrier potential



15. When the graph between current through and voltage across a device is a straight line, the device is referred to as ........

(i) linear 
(ii) active
(iii) nonlinear 
(iv) passive



16. When the crystal diode current is large, the bias is ........

(i) forward 
(ii) inverse
(iii) poor 
(iv) reverse



17. A crystal diode is a ........ device.

(i) non-linear 
(ii) bilateral
(iii) linear 
(iv) none of the above



18. A crystal diode utilities ........ characteristic for rectification.

(i) reverse 
(ii) forward
(iii) forward or reverse
(iv) none of the above



19. When a crystal diode is used as a rectifier, the most important consideration is ........

(i) forward characteristic
(ii) doping level
(iii) reverse characteristic
(iv) PIV rating



20. If the doping level in a crystal diode is increased, the width of depletion layer ........

(i) remains the same
(ii) is decreased
(iii) is increased
(iv) none of the above



21. A zener diode has ........

(i) one pn junction
(ii) two pn junctions
(iii) three pn junctions
(iv) none of the above



22. A zener diode is used as ........

(i) an amplifier 
(ii) a voltage regulator
(iii) a rectifier 
(iv) a multivibrator



23. The doping level in a zener diode is ........ that of a crystal diode.

(i) the same as 
(ii) less than
(iii) more than 
(iv) none of the above



24. A zener diode is always .......... connected.

(i) reverse
(ii) forward
(iii) either reverse or forward
(iv) none of the above



25. A zener diode utilises ........ characteristic for its operation.

(i) forward
(ii) reverse
(iii) both forward and reverse
(iv) none of the above



26. In the breakdown region, a zener diode behaves like a ......... source.

(i) constant voltage
(ii) constant current
(iii) constant resistance
(iv) none of the above



27. A zener diode is destroyed if it ........

(i) is forward biased
(ii) is reverse biased
(iii) carries more than rated current
(iv) none of the above



28. A series resistance is connected in the zener circuit to ........

(i) properly reverse bias the zener
(ii) protect the zener
(iii) properly forward bias the zener
(iv) none of the above



29. A zener diode is ........ device.

(i) a non-linear 
(ii) a linear
(iii) an amplifying 
(iv) none of the above



30. A zener diode has ........ breakdown voltage.

(i) undefined 
(ii) sharp
(iii) zero 
(iv) none of the above



31. ........ rectifier has the lowest forward resistance.

(i) solid state 
(ii) vacuum tube
(iii) gas tube 
(iv) none of the above



32. Mains a.c. power is converted into d.c. power for ........

(i) lighting purposes
(ii) heaters
(iii) using in electronic equipment
(iv) none of the above



33. The disadvantage of a half-wave rectifier is that the ........

(i) components are expensive
(ii) diodes must have a higher power rating
(iii) output is difficult to filter
(iv) none of the above



34. If the a.c. input to a half-wave rectifier has an r.m.s. value of 400/√2 volts, then diode PIV rating is ........

(i) 400/√2 V 
(ii) 400 V
(iii) 400 ×√2 V 
(iv) none of the above



35. The ripple factor of a half-wave rectifier is ........

(i) 2 
(ii) 1.21
(iii) 2.5 
(iv) 0.48



36. There is a need of transformer for ........

(i) half-wave rectifier
(ii) centre-tap full-wave rectifier
(iii) bridge full-wave rectifier
(iv) none of the above



37. The PIV rating of each diode in a bridge rectifier is ........ that of the equivalent centretap rectifier.

(i) one-half 
(ii) the same as
(iii) twice 
(iv) four times



38. For the same secondary voltage, the output voltage from a center-tap rectifier is ........ than that of bridge rectifier.

(i) twice 
(ii) thrice
(iii) four times 
(iv) one-half



39. If the PIV rating of a diode is exceeded, ........

(i) the diode conducts poorly
(ii) the diode is destroyed
(iii) the diode behaves as zener diode
(iv) none of the above



40. A 10 V power supply would use ........ as filter capacitor.

(i) paper capacitor 
(ii) mica capacitor
(iii) electrolytic capacitor
(iv) air capacitor



41. A 1000 V power supply would use ........ as a filter capacitor.

(i) paper capacitor
(ii) air capacitor
(iii) mica capacitor
(iv) electrolytic capacitor



42. The ...... filter circuit results in the best voltage regulation.

(i) choke input
(ii) capacitor input
(iii) resistance input
(iv) none of the above



43. A half-wave rectifier has an input voltage of 240 V r.m.s. If the step-down transformer has a turns ratio of 8 : 1, what is the peak load voltage ? Ignore diode drop.

(i) 27.5 V 
(ii) 86.5 V
(iii) 30 V 
(iv) 42.5 V



44. The maximum efficiency of a half-wave rectifier is ...........

(i) 40.6% 
(ii) 81.2%
(iii) 50% 
(iv) 25%



45. The most widely used rectifier is ...........

(i) half-wave rectifier
(ii) centre-tap full-wave rectifier
(iii) bridge full-wave rectifier
(iv) none of the above