Điện tử: Chap 1

c

An advantage of the miniaturization of electronic devices is that they ________. a. reduce cost b. improve reliability c. increase speed d. increase availability

c

QN=44 In a p-type material, the minority carriers are ________. a. conduction-band electrons b. valence-band holes c. conduction-band electrons d. valence-band electrons

d

QN=45 Pentavalent atoms are often referred to as ________. a. acceptor atoms b. minority carriers c. majority carriers d. donor atoms

b

Electrons are the minority carriers in an n-type material. A.True B.False

a

A free electron has a higher energy state than any that are bound to their nucleus. A. True B. False

a

A normalized value has a reference magnitude of one. A. True B.False

a

An LED light is expected to last for ________. A. 25000 hours B. 2000 hours C. 10000 hours D. 5000 hours

a

An LED produces visible or invisible light when ________. A. the electrons and the holes combine with each other B. the electrons and the holes combine in the diffusion region C. a hole enters the diffusion region D. an electron enters the diffusion region

a

An intrinsic semiconductor is one that is as pure as present-day technology can make it. A. True B. False

a

As semiconductor devices have become ________ one of the primary purposes of the container is simply to provide a means for physical handling. A. miniaturized B. larger C. widely used D. more powerful

a

Holes are the majority carriers in a p-type material. A. True B. False

c

In the Zener region the current ________ and the voltage across the diode ________. A. is almost constant; is almost constant B. can increase a lot; can increase a lot C. can increase a lot; is almost constant D. is almost constant; can increase a lot

a

Light-emitting diodes emit light when the p-n junction is ________. A. forward-biased B. operating in the Zener region C. zero biased D. reverse-biased

a

QN=43 Silicon diodes have been more significantly developed than germanium because ________. a. it is cheaper b. it has a lower forward voltage drop c. it is more tolerant of heat d. it is easier to produce

d

QN=42 The diode electrode with n-type material is called the ________. a. anode b. Zener region c. depletion region d. cathode

c

QN=31 Which of the following is not a commonly used semiconductor material'? a. germaniun b. silicon c. lead d. carbon

a

QN=32 As the device temperature increases, semiconductor materials tend to have ________. a. an increasing number of free electrons b. an increasing number of free electrons c. relatively unchanged conduction conduction levels d. lower conduction levels

c

QN=33 Pentavalent elements have ________ valence electrons. a. 3 b. 1 c. 5 d. 4

a

QN=34 Doping is used to ________. a. increase the conductivity of an intrinsic semiconductor b. decrease the conductivity of an intrinsic semiconductor c. increase the insulative quality of an intrinsic semiconductor d. stabilize the conductivity of an intrinsic semiconductor

a

QN=35 When pentavalent elements are used in doping, the resulting material is called ________ material and has an excess of ________. a. n-type; conduction-band electrons b. n-type; valence-band holes c. p-type; valence-band holes d. p-type; conduction-band electrons

b

QN=36 When trivalent elements are used in doping, the resulting material is called ________ material and has an excess of ________. a. p-type; conduction-band electrons b. p-type; valence-band holes c. n-type; valence-band holes d. n-type; conduction-band electrons

c

QN=37 In an n-type material, the majority carriers are ________. a. conduction-band holes b. valence-band holes c. conduction-band electrons d. valence-band electron

d

QN=38 The energy required to move an electron in silicon from the valence band to the conduction band is ________. a. 0.67 eV b. 1.8 eV c. 10 eV d. 1.1 eV

b

QN=39 When a p-n junction's depletion layer is narrowed and the device acts as a nearly perfect conductor, it is ________. a. reverse-biased b. forward-biased c. unbiased d. None of the above

a

QN=40 The maximum reverse bias potential that can be applied to a Zener diode before it enters the Zener region is called the ________. a. PIV b. depletion voltage c. barrier voltage d. threshold voltage

b

QN=41 When a p-n junction is reverse-biased, the depletion layer is ________ and the device acts as a near-perfect ________. a. narrowed; conductor b. widened; insulator c. widened; conductor d. narrowed; insulator

c

QN=46 When a p-n junction is reverse-biased, its junction resistance is ________. a. determined by the components that are external to the device b. low c. high d. constantly changing

a

QN=47 A p-n junction is forward biased when ________. a. the applied potential causes the n-type material to be more negative than the p-type material. b. the applied potential causes the n-type material to be more positive than the p-type material. c. both materials are at the same potential d. None of these

d

QN=48 A p-n junction is reverse biased when ________. a. the applied potential causes the p-type material to be more negative than the n-type material b. the applied potential causes the n-type material to be more positive than the p-type material c. the current flow across the junction is based on minority carrier transfer d. All of the above

a

QN=49 The isolated atomic energy structure associated with electron orbital shells is called a/an ________. a. energy band b. conduction band c. valence band d. energy gap

b

QN=50 The diode electrode with p-type material is called the ________. a. cathode b. anode c. Zener region d. depletion region

b

QN=51 The diffusion capacitance of a diode is a shunt capacitance effect that occurs when the diode ________. a. is reverse biased b. is forward biased c. is large d. is small

b

QN=52 The transition capacitance of a diode is a shunt capacitive effect that occurs when the diode ________. a. is small b. is reverse-biased c. is large d. is forward-biased

a

QN=53 When tested with an ohmmeter, a diode should have a relatively high resistance for ________ condition. a. the reverse-biased b. both reverse and forward-biased c. the forward-biased d. zero-biased

b

QN=54 When tested with an ohmmeter, a diode should have a relatively small resistance for ________ condition. a. zero-biased b. the forward-biased c. the reverse-biased d. both reverse- and forward-biased

a

QN=55 The nominal voltage for a 1N961 Fairchild 10-V Zener diode has a temperature coefficient of 0.072. If the temperature increases by 50° C, what is the change in V? a. 0.36 V b. 0.108 V c. 0.72 V d. 0.54 V

b

QN=56 The act of giving off light by applying an electrical source of energy is called ___. a. light power b. electroluminescence c. photons d. laser

a

Si and Ge both have negative temperature coefficients. A. True B. False

a

Some of the modern ohmmeters have a diode test setting. If you do not have one of these ohmmeters then to test the diode you need to check its resistance in the forward and the reverse direction. These resistances should be ________. A. relatively low in the forward direction and relatively high in the reverse direction B. relatively high in the forward direction and relatively low in the reverse direction C. relatively high in the forward direction and relatively high in the reverse direction D. relatively low in the forward direction and relatively low in the reverse direction

b

Suppose that a particular Zener diode has a temperature coefficient of 0.00575. If the temperature of this Zener diode increases by 50° C, what is the change in Vz? A. 5 × 0.00575 = 0.02875 B. 50 × 0.00575 = 0.2875 C. 10 × 0.00575 = 0.0575 D.Cannot tell without looking at the circuit in which the Zener is used

c

The ________ diode is a short circuit for the region of conduction and it is an open circuit in the region of nonconduction a. power b. typical c. ideal d. small-signal

a

The amount of energy that is converted to heat at a silicon p-n junction can be a significant design consideration. A. True B. False

a

The amount of photon energy emitted at the p-n junction of a silicon diode is negligible. A. True B. False

c

The characteristic of an ideal diode are those of a switch that can conduct current ________. A. in both directions but in only one direction at a time B.in both directions C.in one direction only D.depends on the circuit it is used in

b

The characteristics of an ideal diode are those of a switch that can conduct current in ________. a. the reverse bias direction b. only one direction c. both directions d. None of the above

b

The ideal diode symbol has an arrow that points in the direction of ________ a. positive terminal under forward bias b. the forward current flow c. the leakage current flow d. All of the above

b

The piecewise linear model, equivalent circuit of the diode consists of ________. A.the ideal diode B.a battery, a small resistor, and the ideal diode C.a junction capacitor, a battery, a small resistor, and the ideal diode D.a battery and the ideal diode

b

The quantum-Volt (qV) is the unit of measurement for electron energy. A. True B. False

a

The reverse breakdown voltage of an LED is typically less than 12 V. A. True B. False

c

The term ________ is applied to a material that has a conductivity level somewhere between the extremes of conductivity. a. conductor b. ionic c. semiconductor d. insulator

b

The term ________ is applied to a material that offers a very low level of conductivity under pressure from an applied voltage a. ionic b. insulator c. semiconductor d. conductor

b

The term ________ is applied to any material that supports a generous flow of charge when a voltage source of limited magnitude is applied across its terminals. a. semiconductor b. conductor c. insulator d. dielectric

c

The typical range of the ac resistance of a diode in the active region is ________. A. 1 Ω to 10 Ω B.100 Ω to 500 Ω C.1 Ω to 100 Ω D.50 Ω to 100 Ω

a

When silicon is doped with either a pentavalent or a trivalent impurity its resistance will ________. A. decrease B. increase C.make the resistance stable against variation due to temperature D. None of the above

c

Which material(s) are commonly used in high-speed applications? A.Si exclusively B.Si and Ge C.GaAs and Ge D.GaAs and Si