Free Printable Semiconductor Diodes and Optoelectronics B1b-8

1.

Which type of material has characteristics that fall between those of conductors and insulators?

a)

A. Intrinsic

b)

B. Bipolar

c)

C. Reactive

d)

D. Semiconductor

2.

Which at the following is NOT a pure semiconductor element (material)?

a)

A. Silicon

b)

B. Platinum

c)

C. Carbon

d)

D. Germanium

3.

The outermost orbit of electrons is called the:

a)

A. Valence

b)

B. Nucleus

c)

C. Junction

d)

D. Depletion region

4.

Which sentence best describes convalent bonding?

a)

A. When the nucleus of the various atoms are attracted to each other.

b)

B. When all the atoms share protons with other atoms.

c)

C. Atoms that are bonded by virtue of electric charges.

d)

D. Atoms that share their valence electrons with other atoms.

5.

How many valence electrons are in pure silicon and pure germanium?

a)

A. 1

b)

B. 2

c)

C.4

d)

D. 6

6.

Conduction in Pure Germanium and Silicon

What is necessary for silicon to conduct current as an ordinary conductor?

a)

A. Extremely high temperatures.

b)

B. Extremely low temperatures

c)

C. More than 1 volt applied.

d)

D. More than 1 ampere of current.

7.

What is a “hole” in a covalent bond?

a)

A. It is a net negative charge.

b)

B. It is where the charge is zero.

c)

C. It is the absence of an electron in ther valence orbit.

d)

D. When the positive and negative ions have been concelled out.

8.

Conduction in Doped Germanium and Silicon

What does “doping” mean when referring to semiconductor material?

a)

A. It is the process of addin impurites to the material.

b)

B. It is the process of creating a negative ion.

c)

C. It is the provess of creating postive ion.

d)

D. It is the process of removing all impurities from the material.

9.

What does “pentavalent” mean?

a)

A. There is one valence electrons

b)

B. There are two valence electrons.

c)

C. There are three valence elcetrons

d)

D. There are five valence electrons.

10.

What does “trivalent” mean?

a)

a) There is one valence electron.

b)

b) There are two valence electrons.

c)

c) There are three valence electrons.

d)

d) There are five valence electrons

11.

When arsenic is added to silicon, what occurs with the valence structure in the semiconductor material?

a)

a) It becomes an ionic bond.

b)

b) It gives its extra free electron away.

c)

c) It creates a balance valence so the material acts as an insulator.

d)

d) It creates a “hole” in the electron structure so an electron can flow from one covalent bond to the next.

12.

When indium is added to silicon, what occurs with the valence structure in the semiconductor material?

a)

a) It becomes an ionic bond.

b)

b) It gives its extra free electron away.

c)

c) It creates a balance valence so the material acts as an insulator.

d)

d) It creates a “hole” in the electron structure so an electron can flow from one covalent bond to the next.

13.

The “N” in “N-type” material means “negative”. Which of the following describes N-type semiconductor material?

a)

a) There are extra (free) electrons in the material.

b)

b) It is made from a material other than silicon or germanium.

c)

c) It has been doped to create ionic rather than covalent bonds.

d)

d) The number of holes exceed the number of (free) electrons in the material.

14.

The “P” in “P-type” material means “positive”. Which of the following describes P-type semiconductor material?

a)

a) There are extra (free) electrons in the material.

b)

b) It is made from a material other than silicon or germanium.

c)

c) It has been doped to create ionic rather than covalent bonds.

d)

d) The number of holes exceed the number of (free) electrons in the material.

15.

PN Junctions

What is the “junction” in a diode?

a)

a) The location where the wires (leads) are attached to the semiconductor materials.

b)

b) The area where the two channels (N channel and P channel) meet the intrinsic material.

c)

c) The area where N-type and P-type materials are joined together

d)

d) The location where the ionic bonds are the strongest in the semiconductor lattice.

16.

Which of the following best describes the “depletion region” in a junction diode?

a)

a) It is when the positive charge is at its strongest.

b)

b) It is when the negative charge is at its strongest.

c)

c) It is when the free electrons in the P-type material break some of the covalent bonds and allow the diode to act as an open circuit.

d)

d) It is when some of the free electrons (mobile charges) in the vicinity of the junction move across the junction and fill some of the “holes” in the P-type material.

17.

Which of the following best describes the “barrier voltage”?

a)

a) It is the voltage that was attached to the semiconductor material as it was being manufactured.

b)

b) It is the voltage created by the opposite charges that build up on each side of the junction.

c)

c) It is the voltage drop across a reverse biased diode only – not across a forward biased diode.

d)

d) It is the maximum voltage that the diode can handle reverse biased.

18.

The “barrier voltage” of a silicon PN junction is approximately:

a)

A. 0.3V

b)

B. 0.7V

c)

C. 1.2V

d)

D. 1.4V

19.

The “barrier voltage” of a germanium PN junction is approximately:

a)

A. 0.3V

b)

B. 0.7V

c)

C. 1.2V

d)

D. 1.4V

20.

In the space next to the statement, write an F if it is true for a forward biased diode, or write an R if it is true for a reverse biased diode.

20. The free electrons in the N material are attracted to the positive terminal of the voltage source. This increases the number of positive ions in the area of the PN junction, which increases the width of the depletion region on the N side of the junction.

(a)

21.

21. The diode resistance is small.

(a)

22.

22. The voltage source supplies a constant follow of electrons, which drift through the N-type material along with the free electrons contained within it. The “holes” in the P material will also drift toward the junction.

(a)

23.

23. The depletion region is wider.

(a)

24.

24. The positive terminal of the external voltage source is connected to the N material.

(a)

25.

25. The free electrons that accumulate on the P side of the junction are attracted by the positive terminal, cancelling the negative charge on the P side.

(a)

26.

26. Electrons also leave the negative terminal of the voltage source and enter the P material. These electrons fill the holes near the PN junction, causing the holes to move toward the negative terminal, which increased the width of the PN junction.

(a)

27.

27. The positive terminal of the external voltage source is connected to the P material.

(a)

28.

28. Current will flow through when connected this way but will flow only if the external voltage is greater than the barrier voltage.

(a)

29.

29. Current will flow, but in microamperes or nanoamperes (a small leakage current).

(a)

30.

30. The current that flows through a diode when connected this way is limited by the resistance of the P and N materials and the external resistance of the circuit.

(a)

31.

31. The negative terminal of the external voltage source is connected to the P material.

(a)

32.

32. The negative terminal of the external voltage source is connected to the N material.

(a)

33.

Diode Characteristics

The maximum forward current is labelled:

a)

a) I_F max.

b)

b) PIV.

c)

c) I_Z total.

d)

d) MFC.

34.

The maximum safe reverse voltage is called:

a)

a) Barrier voltage (BV)

b)

b) Junction voltage (JV)

c)

c) Peak inverse voltage (PIV)

d)

d) Peak to Peak voltage (V_P-P)

35.

The N section of the diode is called the:

a)

a) Anode

b)

b) Base

c)

c) Cathode

d)

d) Depletion Region

36.

The P section of the diode is called the:

a)

a) Anode

b)

b) Base

c)

c) Cathode

d)

d) Depletion Region

37.

The N section of the diode is represented by the:

a)

a) Arrow (triangle).

b)

b) Bar.

c)

c) Circle.

d)

d) Zig-zag line

38.

The P section of the diode is represented by the:

a)

a) Arrow (triangle).

b)

b) Bar.

c)

c) Circle.

d)

d) Zig-zag line

39.

Testing PN Junction Diodes

Which of the following can be used to test a diode:

a)

a) Oscilloscope

b)

b) Ohmmeter

c)

c) Ammeter

d)

d) Wheatstone Bridge

40.

The forward resistance (when connected forward biased) of a silicon diode should be:

a)

a) Less than 100 ohms.

b)

b) Hundreds of ohms.

c)

c) Tens of thousands of ohms.

d)

d) More than hundreds of thousands of ohms.

41.

The reverse resistance (when connected reverse biased) of a silicon diode should be:

a)

a) Less than 100 ohms.

b)

b) Hundreds of ohms.

c)

c) Tens of thousands of ohms.

d)

d) More than hundreds of thousands of ohms.

42.

When using an ohmmeter, the red meter lead is:

a)

a) Negative.

b)

b) Positive.

c)

c) Not powered.

43.

When a diode is shorted, what would be indicated during testing?

a)

a) Low resistance in the forward and reverse directions.

b)

b) High resistance in the forward and reverse directions.

44.

When a diode is open, what would be indicated during testing?

a)

a) Low resistance in the forward and reverse directions.

b)

b) High resistance in the forward and reverse directions.

45.

Zener Diode Characteristics

What happens within a Zener diode that is reverse biased when the reverse voltage increases?

a)

a) Its resistance increases.

b)

b) Its resistance decreases.

c)

c) Current flow stops.

46.

What happens with the ability of a reverse-biased Zener diode to dissipate power as the temperature increases?

a)

a) Its ability to dissipate power increases

b)

a) Its ability to dissipate power increases

47.

Which of the following characteristic of a Zener diode helps to determine its power dissipation rating?

a)

a) Lead length – longer lead lengths dissipate more power

b)

b) Lead length – shorter lead lengths dissipate more power

c)

c) Case size – larger case size dissipates more power

d)

d) Case size – smaller case size dissipated more power

48.

Zener Diode Ratings

Which Zener diode rating gives the maximum reverse current that can flow in a Zener diode without exceeding the power dissipation rating?

a)

a) The peak inverse current rating (I_PIV).

b)

b) The maximum barrier current (I_BM)

c)

c) The peak Zener conduction current (I_PZC)

d)

d) The maximum Zener current (I_ZM)

49.

What is the difference between the maximum Zener current and the reverse current for a Zener diode?

a)

a) The maximum Zener current (I_ZM) represents the leakage current before breakdown.

b)

b) The reverse current (I_R) represents the leakage current before breakdown

50.

How is the Zener reverse current specified?

a)

a) How is the Zener reverse current specified?

b)

b) It is specified at a certain reverse voltage (E_R) and is approximately 80% of Zener voltage (E_Z).

c)

c) It is approximately 60% of Zener current (I_Z).

d)

d) It is approximately 80% of Zener current (I_Z).

51.

Voltage Regulation with Zener Diodes

What is the purpose of having a resistor in series with a Zener diode in a typical Zener voltage diode regulator circuit?

a)

a) It helps stabilize the Zener voltage drop.

b)

b) It provides thermal stability for the Zener’s operational limits.

c)

c) It provides an alternative pathway for current to flow when the Zener is not operational.

d)

d) It allows a place for the voltage to “drop” that is between the Zener’s breakdown voltage and the input voltage.

52.

What happens to current in a Zener diode (that is part of a regulator circuit) as the input voltage increases?

a)

a) The current through the Zener diode increases.

b)

b) The current through the Zener diode decreases.

53.

What happens to the Zener diode’s breakdown voltage as the input voltage changes?

a)

a) The Zener’s breakdown voltage will also change.

b)

b) The Zener’s breakdown voltage will remain the same.

54.

What happens to the internal resistance of the Zener diode as the current through the Zener increases?

a)

a) The internal resistance increases.

b)

b) The internal resistance decreases.

55.

Testing Zener Diodes

What can be learned by testing Zener diodes with an ohmmeter?

a)

a) The Zener voltage rating.

b)

b) The Zener power dissipation rating.

c)

c) The Zener maximum current rating.

d)

d) Whether the Zener is open, shorted, and/or has leakage.

56.

Can an ohmmeter tell if the Zener diode is regulating at the rated value?

a)

a) Yes it can.

b)

b) No it can’t.

57.

What is the best way to tell if a Zener diode is regulating at the rated value?

a)

a) Placing it in series with a regular PN junction diode.

b)

b) Placing it in parallel with another Zener diode of the same rated value.

c)

c) Observe the Zener voltage on an oscilloscope.

d)

d) A regulation test must be performed with a metered power supply that can indicate both voltage and current.

58.

Light-Sensitive Devices

Which of the following is true about of photoconductive cells (photo cells)?

a)

a) The resistance change is proportional to the amount of light striking it.

b)

b) The voltage created is proportional to the amount of light striking it

c)

c) The resistance change is inversely proportional to the amount of light striking it.

d)

d)The voltage created is inversely proportional to the amount of light striking it.

59.

This device convers light energy directly into electrical energy.

a)

a) Photoconductive cell (photo cell)

b)

b) Photovoltaic cell (solar cell)

c)

c) Photodiode

d)

d) PIN photodiode

e)

e) Phototransistor

60.

This device works like a photodiode but had three leads and two PN junctions.

a)

a) Photoconductive cell (photo cell)

b)

b) Photovoltaic cell (solar cell)

c)

c) Photodiode

d)

d) PIN photodiode

e)

e) Phototransistor

61.

This device responds to lower light frequencies than other devices.

a)

a) Photoconductive cell (photo cell)

b)

b) Photovoltaic cell (solar cell)

c)

c) Photodiode

d)

d) PIN photodiode

e)

e) Phototransistor

62.

In these devices, the internal resistance changes with a change in

light.

a)

a) Photoconductive cell (photo cell)

b)

b) Photovoltaic cell (solar cell)

c)

c) Photodiode

d)

d) PIN photodiode

e)

e) Phototransistor

63.

Which device can be described like this:

Light striking the surface of the solar cell knocks valence electrons from their orbits. The electrons near the depletion region are drawn to the N-type material producing a small voltage across the PN junction.

a)

a) Photoconductive cell (photo cell)

b)

b) Photovoltaic cell (solar cell)

c)

c) Photodiode

d)

d) PIN photodiode

e)

e) Phototransistor

64.

The efficiency of solar cell (the amount of light energy striking it that is converted to electricity is approximately:

a)

a) 15% to 20%

b)

b) 20% to 25%

c)

c) 60% to 65%

d)

d) 80% to 85%

65.

The average voltage output of a solar cell is about:

a)

a) 0.45V.

b)

b) 0.7V.

c)

c) 1.5V

d)

d) 12V

66.

A photodiode is connected:

a)

a) Forward biased

b)

b) Reverse biased.

67.

Light-Emitting Diodes (LED’s)

An LED:

a)

a) Converts light energy to electrical energy.

b)

b) Converts electrical energy to light energy.

c)

c) Converts light energy to resistance.

d)

d) Converts a specific light frequency to a different light frequency.

68.

The forward bias voltage of an LED:

a)

a) Must exceed 0.7V before a current can flow.

b)

b) Must exceed 1.2V before a current can flow.

c)

c) Must exceed 3V before a current can flow.

d)

d) Is approximately 1/10 of its peak inverse voltage.

69.

LED’s are connected:

a)

a) Forward biased.

b)

b) Reverse biased.

70.

What is the purpose of a resistor placed in series with an LED?

a)

a) The resistor creates the necessary bias voltage for the LED to conduct in a linear mode.

b)

b) The resistor limits the voltage drop across the LED so that it is operating under its breakthrough voltage.

c)

c) The resistor allows the LED to dissipate more energy (glow brighter).

d)

d) The resistor limits current flow through the LED. Excessive current will damage the LED.

71.

What is the purpose of an optocoupler?

a)

a) It allows a small signal to switch a load with a much higher current requirement.

b)

b) It is a device that is used in amplifiers to give a visual representation of the created power.

c)

c) It is an LED used in conjunction with a phototransistor. It allows a signal to pass through while providing a high degree of electrical isolation.

d)

d) Is an LED and used in conjunction with a thyristor. It allows optical control of an electrical circuit.

Semiconductor Diodes and Optoelectronics B1b-8

Total questions: 71

Worksheet time: 42mins

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