semiconductor theory Mcqs
1. In the depletion region of a pn junction, there is a shortage of_________________?
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A. Donor ions

B. None of the above

C. Acceptor ions

D. Holes and electrons
2. A semiconductor has ______________ temperature coefficient of resistance?
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A. Zero

B. None of the above

C. Negative

D. Positive

3. The resistivity of a pure silicon is about _______________?
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A. 6000 O cm

B. 6 x 10-8 O cm

C. 100 O cm

D. 3 x 105 O m

4. A reverse bias pn junction has_____________?
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A. Very narrow depletion layer

B. Almost no current

C. Large current flow

D. Very low resistance

5. The resistivity of pure germanium under standard conditions is about_______________?
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A. 6 x 10-4 cm

B. 60 x cm

C. 6 x 104 cm

D. 3 x 106 cm

6. The leakage current in a pn junction is of the order of________________?
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A. kA

B. mA

C. Aa

D. A
7. The leakage current across a pn junction is due to________________?
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A. Minority carriers

B. Junction capacitance

C. Majority carriers

D. None of the above

8. A hole and electron in close proximity would tend to________________?
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A. None of the above

B. Repel each other

C. Attract each other

D. Have no effect on each other

9. The random motion of holes and free electrons due to thermal agitation is called______________?
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A. Diffusion

B. None of the above

C. Pressure

D. Ionisation

10. Addition of pentavalent impurity to a semiconductor creates many________________?
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A. Bound electrons

B. Valence electrons

C. Free electrons

D. Holes

11. In an intrinsic semiconductor, the number of free electrons_____________?
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A. None of the above

B. Is greater than the number of holes

C. Is less than the number of holes

D. Equals the number of holes
12. When the temperature of an extrinsic semiconductor is increased, the pronounced effect is on_________________?
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A. Junction capacitance

B. Minority carriers

C. Majority carriers

D. None of the above

13. At absolute temperature, an intrinsic semiconductor has________________?
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A. Many free electrons

B. A few free electrons

C. No holes or free electrons

D. Many holes

14. The barrier voltage at a pn junction for germanium is about________________?
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A. 0.3 V

B. 5 V

C. 3 V

D. Zero

15. With forward bias to a pn junction , the width of depletion layer__________________?
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A. Increases

B. Decreases

C. Remains the same

D. None of the above

16. As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor_______________?
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A. Decreases

B. Remains the same

C. Increases

D. None of the above

17. In a semiconductor, current conduction is due to________________?
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A. None of the above

B. Holes and free electrons

C. Only holes

D. Only free electrons

18. A semiconductor is formed by ______________bonds?
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A. None of the above

B. Co-ordinate

C. Electrovalent

D. Covalent
19. The impurity level in an extrinsic semiconductor is about_______________of pure semiconductor ?
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A. 1 atom for 100 atoms

B. 1 atom for 108 atoms

C. 1 atom for 104 atoms

D. 10 atoms for 108 atoms

20. Addition of trivalent impurity to a semiconductor creates many_______________?
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A. Free electrons

B. Bound electrons

C. Valence electrons

D. Holes
21. The battery connections required to forward bias a pn junction are_________________?
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A. None of the above

B. +ve terminal to p and ve terminal to n

C. #NAME?

D. #NAME?

22. At room temperature, an intrinsic semiconductor has_______________?
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A. A few free electrons and holes

B. No holes or free electrons

C. Many free electrons only

D. Many holes only

23. A pentavalent impurity has______________Valence electrons?
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A. 4

B. 3

C. 6

D. 5
24. A forward biased pn junction diode has a resistance of the order of_____________?
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A. O

B. kO

C. None of the above

D. MO

25. A hole in a semiconductor is defined as_________________?
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A. strong>. A free proton

B. The incomplete part of an electron pair bond

C. A free electron

D. A free neutron

26. When a pure semiconductor is heated, its resistance_________________?
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A. Remains the same

B. Goes up

C. Cant say

D. Goes down
27. The strength of a semiconductor crystal comes from______________?
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A. Forces between protons

B. Electron-pair bonds

C. None of the above

D. Forces between nuclei

28. The most commonly used semiconductor is________________?
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A. Sulphur

B. Germanium

C. Silicon

D. Carbon

29. When a pentavalent impurity is added to a pure semiconductor, it becomes________________?
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A. An intrinsic semiconductor

B. An insulator

C. n-type semiconductor

D. p-type semiconductor

30. A trivalent impurity has______________valence electrons?
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A. 5

B. 6

C. 4

D. 3
31. An n-type semiconductor is______________?
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A. Electrically neutral

B. Negatively charged

C. Positively charged

D. None of the above

32. A reverse biased pn junction has resistance of the order of________________?
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A. O

B. kO

C. None of the above

D. MO
33. At room temperature, an intrinsic silicon crystal acts approximately as_______________?
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A. A conductor

B. An insulator

C. A piece of copper wire

D. A battery

34. A pn junction acts as a__________________?
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A. Unidirectional switch

B. Bidirectional switch

C. Controlled switch

D. None of the above

35. A semiconductor has generally_______________valence electrons?
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A. 3

B. 2

C. 4

D. 6