CHAPTER 9 – MODERN ELECTRONICS
OFFICIAL GOVERNMENT TEST BANK - - CHAPTER 9
1. Which of the following exhibits zero resistance below a critical temperature?
A. Insulator
C. semiconductor
B. conductor
D. superconductor
2. Which of the following exhibits very high resistance?
a. insulator
b. conductor
c. semiconductor
d. superconductor
3. Which of the following exhibits properties of both a conductor and a resistor?
a. glass rod
b. copper wire
c. semiconductor
d. superconductor
4. Electrons are NEVER free to move within a solid and carry electric current is a(n)
a. insulator.
b. conductor.
c. semiconductor.
d. superconductor.
5. Which statement is NOT correct?
a. Valence electrons are electrons in the outermost shell of an atom.
b. The behavior of valence electrons determines the chemical properties of an atom.
c. Valence electrons are tightly bound to the nucleus of an atom.
d. Valence electrons can strongly interact with other atoms.
6. Which of the following is likely to be a valence electron?
a. the innermost electron of a mercury atom
b. an electron in a cobalt atom -. the second-to-outermost energy level
c. an electron in a copper atom in the outermost energy level
d. an electron in a uranium atom in the third-to-outermost energy level
7. A valence electron is an electron
a. in the outermost shell of an atom.
c. in an atom's excited state.
b. that is no longer bound to the atom. d. in an atom's ground state.
8. When identical atoms are far apart, they have ____ energy-level diagrams and ____
wave functions.
a. split; split
b. identical; identical
c. different; different
d. level; split
9. Which solid has a valence band that overlaps the conduction band?
a. conductor
b. semiconductor
c. insulator
d. superconductor
10. Which solid has an empty conduction band and a full valence band?
a. conductor
b. semiconductor
c. insulator
d. superconductor
11. Which solid has a full valence band and a small energy gap?
a. conductor
b. semiconductor
c. insulator
d. superconductor
12. Which solid do the bands in the figure above represent?
a. semiconductor
b. nonconductor
c. insulator
d. superconductor
13. Which solid do the bands in the figure above represent?
a. semiconductor
b. conductor
c. insulator
d. superconductor
14. An energy level that is not occupied by an electron in a semiconductor is a
a. vacancy
b. valance band.
c. diode.
d. hole.
15. The motion of holes in a semiconductor
a. is always in a direction opposite the motion of electrons.
b. is always in the same direction as the motion of electrons. varies with the type of
semiconductor.
d. reverses at regular intervals.
16. In a semiconductor containing only one element or compound,
a. the number of conduction electrons is always greater than the number of holes.
b. there is an equal number of conduction electrons and holes.
c. the number of conduction electrons is always less than the number of holes.
d. there is no relationship between the number of conduction electrons and holes.
17. Charge can move in a substance
a. only in the form of electrons.
b. only as positively charged holes in an electron-poor substance.
c. either in the form of electrons or as positively charged holes in an electron- poor substance.
d. only in the valence band.
ANS: C
DIF: II
OBJ: 24-2.1
18. When adding an impurity to a semiconductor in the process of doping, the impurity
added
a. must have extra valence electrons compared with the atoms in the intrinsic semiconductor.
b. must have fewer valence electrons compared with the atoms in the intrinsic semiconductor.
c. can have either extra valence electrons or fewer valence electrons compared with the atoms
in the intrinsic semiconductor.
d. must have the same number of valence electrons as the atoms in the intrinsic semiconductor
19. If a silicon semiconductor, which has four valence electrons, is doped with atoms
containing three valence electrons,
a. holes can move throughout the material, even if no electrons are in the conduction band.
b. the charge carriers are electrons having negative charges.
c. positive holes that form in the donor level do not move easily.
d. a donor atom occupies an energy level that lies just below the conduction band.
20. When an n-type semiconductor and a p-type semiconductor are brought together to
form a p-n junction, electrons from the _____ layer diffuse toward the ____ layer, and
positive holes are formed in the _____ layer.
a. n; p; n
c. p; n; n
b. p; n; p
d. n, p; p
21. Which statement about a p-n junction is NOT correct?
a. It will allow current to know in a circuit in either direction.
b. The holes and electrons on either side of the p-n junction can migrate across the junction.
c. Electrons from the n side nearest the junction diffuse toward the p side.
d. On the p side nearest the junction, electrons diffuse so that holes move to the inside.
22. At a p-n junction, when a free-moving electron and a free-moving hole meet,
a. mobile charge carriers form.
b. an internal electric field causes further diffusion of electrons and holes.
c. the charges cancel each other, leaving no charge carriers.
d. the depletion region continuously grows larger.
23. If a large enough positive external voltage is applied to the p side of a diode,
a. the electric potential on the negative side is raised compared with the posltive side.
b. the electric potential on the positive side is raised compared with the negative side.
c. the diode is said to be reverse-biased.
d. negative charge carriers cannot move.
24. A P-N junction acts much like a
a. diode.
c. generator.
c. transistor.
d. transducer.
25. If an ac current is sent through a diode, only the ____ component of the current is
transmitted. This is why a diode is a ____.
a. directional; capacitor
b. nonzero; resistor
c. positive; rectifier
d. negative; rectifier
26. The process that converts an alternating current into a direct current using a diode is
a. insulating.
c. doping.
b. superconducting.
d. rectification.
27. When a diode is reverse-biased,
a. the positive part of the original signal is suppressed.
b. it has a very large resistance.
c. the direct current produced is constant.
d. an alternating current is produced.
28. A diode rectifies an alternating current into a
a. reverse-biased current.
b. forward-biased current.
c. constant direct current.
d. pulsed direct current.
29. Which of the following designates a junction transistor?
a. n-p-p
c. n-n-p
b. p-n-p
d. p-p-n
30. Which statement about a p-n-p transistor is NOT correct?
a. A very narrow n region is sandwiched between two p regions.
b. It contains two p-n junctions.
c. The base is more heavily doped than the emitter.
d. The transistor has three leads that can amplify a signal.
31. The circuit symbol shown is for a(n)
a. n-p-n transistor.
b. p-n-p transistor.
c. rectifier.
d. diode.
32. Which statement about junction transistors is NOT correct?
a. If the transistor is properly biased, it acts as a current amplifier.
b. The output current is directly proportional to the input current.
c. Two batteries are necessary to properly bias the transistor.
d. The collector current is inversely proportional to the base current.
33. What can be determined from the graph above?
a. Silver becomes a superconductor above temperature Tc
b. Tin becomes a superconductor at temperature Tc
c. Tin never becomes a superconductor.
d. The resistance of silver goes to zero at temperature Tc
34. Which statement is NOT supported by the graph above?
a. At a temperature of about 10 K, the resistance of silver increases.
b. Tin becomes a superconductor just below a temperature of Tc.
c. The resistance of tin goes to zero at temperature Tc
d. The resistance of silver goes to zero at a temperature of 0 K.
35. Some conductors exhibit nonzero resistance even at absolute zero because
a. their atomic vibrations have too large an amplitude.
b. the resistance steadily decreases as the substance is cooled.
c. the geometric pattern of the crystal in a solid is flawed.
d. the atoms of the lattice are lined up perfectly.
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Question Bank Answer Key
1.C
2.A
3.C
4.A
5.C
6.C
7.A
8.B
9.A
10.C
11.B
12.A
13.C
14.D
15.A
16.B
17.C
18.C
19.A
20.A
21.A
22.C
23.B
24.A
25.C
26.D
27.B
28.D
29.B
30.C
31.B
32.D
33.B
34.D
35.C