$ Chapter 1

1. The _________ is the basic building block of the universe.

2. The 3 principal parts of an atom are the ________, the ________ and the ________.

3. The Proton has a ________ charge.

4. The Electron has a ________ charge.

5. The Neutron has ________ charge.

6. The proton and the neutron combine to form the ________ of an atom.

7. An electron is ________ times larger than a proton.

8. The proton weighs about ________ times more than an electron.

9. The proton is MUCH more massive than the electron. (T or F)

10. The Law of Charges states that ________ charges attract and ________ charges repel.

11. The Law of Centrifugal Force states that _______________________________.

12. The first shell of an atom can have a maximum of ________ electrons.

13. The second shell of an atom can have a maximum of ________ electrons.

14. The third shell of an atom can have a maximum of ________ electrons.

15. The fourth shell of an atom can have a maximum of ________ electrons.

16. The formula for the number of electrons in a shell is __________________ (where N=shell).

17. The outer shell of an atom is the ________ shell.

18. Any electrons in the valence shell are known as ________ electrons.

19. The Valence Shell of an atom cannot hold more than ________ electrons.

20. A Conductor has how many electrons in its Valence Shell ?

21. Which is the best conductor of Silver, Copper and Aluminum?

22. Why is copper the most common conductor?

23. Which is the best insulator of Silver, Copper and Aluminum?

24. Electricity can be defined as ____________________________________.

25. Insulators have ____________ valence electrons.

26. Centrifugal force is proportional to __________ and _________.

27. What are the 3 subatomic parts of atoms and what charge does each carry?

28. How many times larger is an electron that a proton?

29. The weight of a proton is how many times heavier than an electron?

30. State the Law of Charges

31. What force keep the electron from falling into the nucleus of an electon?

32. Materials that make the best conductors have how many valence electrons?

33. Materials that make the best conductors have how many valence electrons?

34. Electricity may be defined as ________________________________.

$ Chapter 2

1. What is a Coulomb?

2. Define the term AMPERE (AMP).

3. Define the term VOLTAGE.

4. Define the term OHM.

5. Define the term WATT.

6. An electric heating element has a resistance of 16 ohms and is connected to a voltage of 120 volts. How much current (amps) will flow in the circuit?

7. How many watts of heat are being produced by a heating element with R=16 ohms and E=120 volts?

8. A 240-volt circuit has a current flow of 20 amps. What is R ?

9. An electric motor has an apparent resistance of 15 ohms. If a current of 8A is flowing through the motro, what is the connected voltage?

10. E=240, R=8, what is I?

11. E=240, R=8, what is W?

12. W=5000, E=240, what is I?

13. W=5000, E=120, what is I?

14. Is it less expensive to use 240V for heating rather than 120V? Explain.

$ Chapter 3

1. What type of meter has a high resistance connected in series with the meter movement?

2. How is a voltmeter connected into the circuit?

3. If a voltmeter has a resistance of 5000 ohms per volt, what is the resistance of the meter when it is set on the 300-volt range?

4. What is the advantage of using a voltmeter that has a high impedance as opposed to a low-impedance meter?

5. What is an analog meter?

6. Why must an ammeter be connected in series with the load?

7. What device is used to change the scale values of an AC ammeter?

8. What is meant by the term "inline" ammeter?

9. A clamp-on ammeter has three turns of wire wrapped around the movable jaw. If the meter is indicating a current of 15 amps, how much current is actually flowing in the circuit?

10. List the three steps for reading a meter.

11. What type of meter contains its own internal power supply?

12. What precaution must be taken when using an ohmmeter?

$ Chapter 4

1. List the three types of electrical circuits.

2. What is the major characteristic of the series circuit?

3. List the three basic rules for series circuits.

4. What is the major characteristic of a parallel circuit?

5. List the three basic rules for the parallel circuit.

6. What type of circuit is used most often in industry and the home?

7. What type of circuit is used the least in industry and the home?

8. Three resistors valued at 300 ohms, 200 ohms, and 600 ohms are connected in series. What is their total resistance?

9. Three resistors valued at 300 ohms, 200 ohms, and 600 ohms are connected in parallel. What is their total resistance?

10. How are fuses and circuit breakers connected in a circuit and why are they connected this way?

$ Chapter 5

1. What is an alternator?

2. What controls the output voltage of an alternator?

3. What controls the frequency of the alternator?

4. How many degrees out of phase with each other are the voltages of a three-phase system?

5. What are the two major types of three-phase connections?

6. List the rules concerning line and phase values of current and voltage in a wye connection.

7. List the rules concerning line and phase values of current and voltage in a delta connection.

8. In a high-leg delta-connected system, what is the voltage between the high leg and neutral?

9. What type of three-phase transformer connection uses only two transformers?

10. How many degrees out of phase are the voltages of a single-phase system?

11. A two-conductor romex cable contains three wires. Which wire is not counted and why?

12. What type of circuit breaker is used to make a 240-volt connection?

13. Where does the grounding conductor connect in a panel?

14. In what two electrical units are fuses rated?

15. It has been calculated that a 290-amp fuse is needed to protect the circuit supplying an air-conditioning compressor. What standard rating of fuse should be used?

16. It has been calculated that a 290-amp fuse is needed to protect the circuit supplying an air-conditioning compressor. What size fuse disconnect will be used for the fuse?

17. What is a dual-element fuse?

$ Chapter 6

1. Name four factors that determine the resistance of wire,

2. A wire has a diameter of .057 inches. What is its circular mil area?

3. What is a mil-foot of wire?

4. When the temperature of wire increases, does its resistance increase or decrease?

5. What determines the voltage rating of wire?

6. What two factors determine the amount of voltage rating a certain type of insulation will have?

7. How much resistance does 75 feet of #24 AWG wire have?

8. If a current of 4 amps flows through the wire in question #7, how much voltage will be dropped by the wire?

$ Chapter 7

1. Name the three basic types of alternating-current loads.

2. What type of load always has its voltage and current in phase with each other?

3. In a pure-inductive circuit, how many degrees out of phase is the current with the voltage?

4. Does the current lead or lag the voltage in question #3?

5. What electrical value is used to measure inductance?

6. What is inductive reactance?

7. What electrical value is used to measure the total opposition to current flow in an AC circuit?

8. What is power factor?

$ Chapter 8

1. What three factors determine the capacitance of a capacitor?

2. What is the dielectric?

3. In what type of field is the energy of a capacitor stored?

4. In a pure-capacitive circuit, how many degrees are the current. and voltage out of phase with each other?

5. Does a capacitive current lead the voltage or lag the voltage?

6. What limits the current in a capacitive circuit?

7. Name two common types of capacitors used in the air-conditioning field.

8. What type of capacitor is generally used as the running capacitor on many air-conditioning compressors?

9. What is the advantage of an AC electrolytic capacitor?

10. What is the disadvantage of an AC electrolytic capacitor?

$ Chapter 9

1. What is a split-phase motor?

2. What are the three basic types of split-phase motors?

3. Explain the difference in construction of run windings and start windings.

4. How many degrees out of phase should be current in the start winding with the current in the run winding to develop maximum starting torque?

5. What type of capacitor is generally used with a capacitor start induction-run motor?

6. Can the micro-farad value of this capacitor be increased to improve starting torque?

7. What type of capacitor is used with a permanent-split capacitor motor?

8. Does the capacitor of a capacitor start induction-run motor help correct power factor?

9. If necessary, can an AC electrolytic capacitor of higher voltage rating be used as the starting capacitor?

10. What is a centrifugal switch used for?

$ Chapter 10

1. What is a shading coil?

2. What determines the synchronous speed of a shaded-pole motor?

3. In general, how is the direction of a shaded-pole induction motor reversed?

4. What type of rotor does the shaded-pole motor contain?

5. Name two advantages of the shaded-pole motor over the split-phase induction motor.

$ Chapter 11

1. Name two ways of changing the speed of a rotating magnetic field.

2. How does the consequent pole motor change speed?

3. Name a disadvantage of the consequent pole motor.

4. Name an advantage of a consequent pole motor.

5. How many steps of speed are common to a multi-speed fan motor?

6. Refer to figure 11-3. Explain what would happen to motor operation if the winding between low and medium should become open.

7. What is an advantage of the multi-speed fan motor over the consequent pole motor?

8. What is a disadvantage of the multi-speed fan motor when compared to the consequent pole motor?

9. How much wire resistance is common for the run winding of most split-phase motors?

10. How much wire resistance is common for the multi-speed fan motor?

$ Chapter 12

1. What are the three basic types of three-phase motors?

2. Name three factors that produce a rotating magnetic field.

3. What is synchronous speed?

4. What two factors determine the synchronous speed of a three-phase motor?

5. How is the direction of rotation of a three-phase motor changed?

6. What is the synchronous speed of a four-pole motor when connected to a 60-Hz line?

7. A dual-voltage three-phase motor has a current draw of 50 amps when connected to a 240-volt line. How much current will flow if the motor is connected for operation on 480 volts?

8. If the stator windings of a three-phase motor are connected for operation on high voltage, will the windings be connected in series or parallel?

9. If a dual-voltage motor is connected for operation on low voltage, and the motor is then connected to high voltage, will the motor operate at a faster speed?

10. Why does a dual-voltage motor draw less current when connected to low voltage than it does when connected to high voltage?

$ Chapter 13

1. What three factors determine the amount of torque produced by an AC induction motor?

2. Why does an AC induction motor draw more current when starting than it does when running?

3. Why does the current flow to the motor increase when load is added to the motor?

4. What does the code letter found on the nameplate of the motor indicate?

5. At what degree angle between the stator current and the rotor current is the maximum torque developed?

6. What type of squirrel cage rotor has the highest starting torque?

7. What type of squirrel cage rotor has the best speed regulation?

8. Why can an induction motor never operate at synchronous speed?

9. What does the locked rotor current of a motor indicate?

10. The nameplate of a squirrel cage motor indicates that the motor has a full-load speed of 875 RPM. How many poles per phase does the motor have?

$ Chapter 14

1. How many slip rings are located on the shaft of the rotor of a wound rotor induction motor?

2. What is the purpose of the slip rings?

3. Name two advantages of the wound rotor motor over the squirrel cage motor.

4. What two factors determine the amount of current flow in the rotor of a wound rotor motor?

5. What does the dashed line drawn between the three resistors shown in figure 14-2 indicate?

6. Why is the starting torque of a wound rotor induction motor higher than the starting torque of a squirrel cage induction motor?

7. The stator of a wound rotor motor has a synchronous speed of 1200 RPM when connected to a 60-Hz line. How many poles per phase are there in the rotor? 8. Refer to figure 14-5. Describe what would happen in this circuit if coil "SI" should be open when the motor started.

9. Refer to figure 14-5. Describe what would happen in this circuit if coil "TR2" should be open when the motor is started.

10. Refer to figure 14-5. Describe what would happen in this circuit if holding contact "M" should become stuck together when the motor is started and not open.

$ Chapter 15

1. Name three characteristics of a synchronous motor that the squirrel cage induction motor and the wound rotor motor do not have.

2. What is an amortisseur winding?

3. How many slip rings are located on the shaft of a synchronous motor?

4. How many slip rings are located on the shaft of a wound rotor induction motor?

5. Is a synchronous motor started with DC excitation voltage applied to the rotor?

6. What is the field discharge resistor used for?

7. A synchronous motor has an eight-pole stator. What will be the speed of the rotor when it is under full load?

8. How is it possible to know when a synchronous motor has normal excitation applied to its rotor?

9. How can a synchronous motor be made to have a leading power factor?

10. What is a synchronous condenser?

$ Chapter 16

1. What are the two basic types of industrial overload units?

2. What is the advantage of the bimetal type of industrial overload unit?

3. Industrial overload units are divided into two sections. What are they?

4. At what percentage of full-load motor current are overload units generally set to trip?

5. When using an industrial type of overload unit, what are the contacts connected in series with?

6. What is the difference between the two types of small overload units'?

7. In the small overload unit which does not contain a heater, what is used to sense the current flow through the motor?

$ Chapter 17

1. What is a solenoid?

2. What type of relays contain a shading coil?

3. What purpose does the shading coil serve?

4. What is the movable part of a relay called?

5. Why is the core material of a relay laminated?

6. What are eddy currents?

7. What effect do eddy currents have on a relay?

8. Why are contact surfaces curved?

9. What is the difference between a relay and a contactor?

10. What is the difference between a contactor and a motor starter?

$ Chapter 18

1. What electronic component is used to control the output of a solid-state relay used to control a DC voltage?

2. What electronic component is used to control the output of a solid-state relay used to control an AC voltage?

3. Explain opto-isolation.

4. Explain magnetic isolation.

5. What is meant by zero switching?

$ Chapter 19

1. What is an isolation transformer?

2. Define a step-up transformer.

3. Define a step-down transformer.

4. The primary of a transformer is connected to 120 volts AC. The secondary has a voltage of 30 volts and is connected to a resistance of 5 ohms. How much current will flow in the primary of the transformer?

5. What is the amount of Control voltage used in most residential air-conditioning systems?

6. What is the amount of control voltage used in most industrial air-conditioning systems?

7. What is the color of the primary leads of most control transformers used for residential service?

8. How many primary windings are generally contained in an industrial control transformer?

9. What is the turns ratio of each of these primary windings as compared to the secondary winding?

10. When an industrial control transformer is to be operated on 480 volts, are the primary windings connected in parallel or series?

$ Chapter 20

1. What are the four types of starting relays?

2. On what type of motor is it necessary to use a starting relay'?

3. What principle is used to operate the hot-wire relay?

4. What principle is used to operate the current relay'?

5. What type of starting relay does not sense motor current to operate?

6. What type of starting relay can be used for overload protection for the motor?

7. What type of motor can the potential relay be used with'?

8. Is the start contact of a hot-wire relay open or closed when power is first applied to the motor'?

9. Is the start contact of a current relay open or closed when power is first applied to the motor'?

10. Refer to the circuit shown in figure 20-4. What would happen if the coil of the current relay were open when the thermostat connected power to the motor circuit?

$ Chapter 21

1. What two types of small AC motors are used with variable-voltage speed control?

2. Why are these two types of motors used?

3. Name two methods of variable-voltage control for small AC motors.

4. What solid-state device is used to control the voltage applied to the motor?

5. Why is it necessary to use only controllers designed for use with inductive loads?

6. Name a method other than variable voltage used to control the speed of small AC motors.

$ Chapter 22

1. What type of motor is used to operate the timer?

2. Why is one of the motor leads brought outside the timer?

3. Name two ways of connecting the defrost timer.

4. What function does the defrost heater perform?

5. To which terminal is the pigtail lead of the timer motor connected if the timer is to operate continuously?

$ Chapter 23

1. What is a thermostat?

2. What is the advantage of an open-contact thermostat?

3. What is the disadvantage of an open-contact thermostat?

4. What is the advantage of a mercury thermostat?

5. What is used to provide a snap action for the contacts in an open-contact type of thermostat?

6. What is used to provide a snap action for the mercury thermostat?

7. What method of sensing temperature is often used with line voltage thermostats?

8. What is a programmable thermostat?

9. What is the advantage of the programmable thermostat?

10. What is a differential thermostat?

11. What are differential thermostats generally used to control?

12. What is antifreeze protection in reference to a differential thermostat?

13. What is the advantage of a low-voltage thermostat over a line voltage thermostat?

14. What is the purpose of the heat anticipator?

15. How is the setting of the heat anticipator generally determined?

$ Chapter 24

1. What device is used to construct most of the pressure switches used in the air-conditioning field?

2. What type of contact is used with a high-pressure switch?

3. What type of contact is used with a low-pressure switch?

4. Where in the refrigerant system is the high-pressure switch connected?

5. Where in the refrigerant system is the low-pressure switch connected?

$ Chapter 25

1. What is a common name for the airflow switch?

2. What function does the airflow switch perform in a circuit?

3. What is interlocking in a control circuit?

$ Chapter 26

1. What is a humidistat?

2. What are the two most common materials used to sense humidity?

3. What type of control is often used to interlock the humidifier with the blower?

$ Chapter 27

1. Why do some fan switches permit the temperature at which the switch will turn off to be set?

2. What type of sensing device do most fan switches use to determine when the temperature is high enough to start the blower fan?

3. What type of contact arrangement is used for switches that control the speed of a condenser fan motor?

4. What is the most common use for a high-limit switch?

5. Why is the blower fan not connected in series with the limit switch?

$ Chapter 28

1. How can the actual amount of useful oil pressure in a condenser be found?

2. What is the function of the current-limiting resistor?

3. Why is the current-limiting resistor center tapped'!

4. Does a high enough oil pressure open the differential pressure switch contacts or close them?

5. What is the function of the heater?

6. Explain the sequence of events that take place if the oil pressure does not become great enough to disconnect the heater circuit.

7. What is the cut-in point?

8. What is the cut-out point?

9. Is the timer circuit connected in series with the motor starter coil?

10. Are the control contacts connected in series with the motor starter coil?

$ Chapter 29

1. What is a solenoid valve?

2. Why is it important not to reverse the connection of the inlet and outlet side of a solenoid valve?

3. What is used to cause the plunger to close when the solenoid coil is de-energized?

4. What is the function of a 4-way reversing valve?

5. What is the function of the pilot valve?

6. What is the function of the main valve?

7. What is actually used to change the position of the main valve from one setting to another?

$ Chapter 30

1. What is short cycling?

2. What is used to provide the timing operation for the short-cycle timer?

3. What type of contacts are used in the short-cycle timer?

4. How many and what type of contacts must the holding relay have?

5. What does the dashed line drawn between the two sets of timer contacts represent?

$ Chapter 31

1. Should a metal bar be heated or cooled to make it expand?

2. What type of metal remains in a liquid state at room temperature?

3. How is a bimetal metal strip made?

4. Why are bimetal strips often formed into a spiral shape?

5. Why should electrical contacts never be permitted to open or close slowly?

6. What two factors determine the amount of voltage produced by a thermocouple?

7. What is a thermopile?

8. What do the letters RTD stand for?

9. What type of wire are RTDs made of?

10. What material is a thermistor made of?

11. , Why is it difficult to measure temperature with a thermistor?

12. , If the temperature of a NTC thermistor increases, will its resistance increase or decrease?

13. How can a silicon diode be made to measure temperature?

14. Assume that a silicon diode is being used as a temperature detector. If its temperature increases, will its voltage drop increase or decrease?

15. What is an above- and below-ground power supply?

$ Chapter 32

1. What are the two basic types of motor controls?

2. Define a schematic diagram.

3. Define a wiring diagram.

4. Components used for the function of stop are generally wired ______________ _______________ and connected in __________.

5. Components used for the function of start are generally wired _______________ ______________ and connected in _________.

6. When reading a schematic diagram, are the components shown in their energized or de-energized position?

7. What does this symbol represent?

8. What does this symbol represent?

9. What does a dashed line drawn between components represent?

10. What is an auxiliary contact?

$ Chapter 33

Refer to circuit 33-1 for the following questions.

1. Explain the action of the circuit if the thermostat should fail to operate.

2. Explain the action of the circuit if FR contacts should become shorted together.

Refer to circuit 33-7 for the following questions.

3. Explain the action of the circuit if the overload (OL) contact should open.

4. Explain the action of the circuit if the pressure switch contacts should become shorted.

5. Explain the action of the circuit if the CR coil should open.

$ Chapter 34

1. What is the purpose of a pilot light?

2. Why is it necessary to be certain that the gas is ignited at the main burner on a call for heat by the thermostat?

3. What is a thermocouple?

4. What is a thermopile?

5. Why must the pilot control valve be reset manually if it should open?

6. Explain how a "fire eye" works.

7. Explain the operation of a "flame rod."

8. What is a common amount of voltage applied to an electric spark ignitor?

9. Why must a ground wire be connected between the direct spark-ignition control module and the burner head?

10. What is the advantage of electric-spark ignition over pilot-light ignition?

$ Chapter 35

1. What is the function of the ignition transformer?

2. How much voltage is supplied to the electrodes?

3. Are the electrodes permitted to enter into the oil spray?

4. What does enter into the oil spray to cause ignition?

5. What device is controlled by the operation of the triac?

6. What solid-state device controls the flow of gate current to the triac?

7. Does the CAD cell have a high resistance or low resistance when in the presence of light?

8. How would the circuit operate if the CAD cell should be in the presence of light when the thermostat called for heat?

$ Chapter 36

1. What is a legend?

2. Refer to figure 36-2. What would be the action of this circuit if the overload relay should bum open?

3. What purpose does the thermistor connected in parallel with the capacitor serve?

4. In figure 36-2, what switch connections are made when the switch is in the HI position?

5. In figure 36-3, why is the thermostat switch shown as a single-pole double- throw?

6.
In figure 36-3, what do the dashed lines showing connection between the start capacitor and start relay to other parts of the circuit mean?

7. In figure 36-3, what color wire is connected between terminal 2 of the thermostat and terminal C of the switch?

8. What color wire is connected between terminal 2 of the thermostat and the start relay?

9. In figure 36-3, if no continuity is shown when one lead of an ohmmeter is connected to switch terminal A and the other is connected to terminal C of the compressor, what does it mean?

10. In figure 36-3, to what two points should the terminals of an ohmmeter be connected to check the continuity of the resistance heater circuit?

$ Chapter 37

1. What does the term CC mean if seen on a control schematic?

2. What does the term CPCS mean if seen on a schematic?

3. Refer to figure 37-2 for the following questions.

4. If it was desired to change the voltage controlling the short-cycle timer from 230 volts to 115 volts, what transformer leads should be connected together?

5. Assume the system has stopped operation. A voltmeter is connected across the LPS switch terminals and it indicates 24 volts. The voltmeter is then connected across the HPS switch and it indicates 0 volts. Which switch is stopping the operation of the circuit?

6. When the system is operating normally, how much voltage should be seen across the CR relay coil? '

$ Chapter 38

1. What is the purpose of terminal markings?

2. What two control components must be in a closed position before a heat pump is permitted to go into the defrost cycle?

3. The thermostat shows a small pilot light connected between terminals Land C. What condition of the thermostat turns this light on?

4. What is the purpose of the outdoor thermostat?

5. What is the operating voltage of the reversing valve solenoid?

$ Chapter 39

Refer to the schematic shown in figure 39-1 for the following questions.

1. The unit will operate normally in the cooling cycle. When the unit is switched to the heating cycle, the gas burner will not ignite. List four possible problems.

2. The blower fan will operate normally in the cooling cycle. In the heating cycle, however, the fan will not operate. List three possible problems.

3. The unit will not operate in the heating or cooling cycle. A voltage check shows that there is no low voltage for operation of the control circuit. List three possible problems.

$ Chapter 40

1. Ice makers are divided into what two major categories?

2. What is the advantage of continually recirculating the water during the ice making process?

3. What component controls the amount of water flow into the original compact ice maker?

4. Does the flex tray ice maker require a mold heater to thaw the ice cubes before they can be dumped into the storage bin?

5. In the original compact ice maker, what method is used to sense when the water has been frozen?

6. In the original compact ice maker, what controls the start of the ejection and refill cycle?

7. In the flex tray ice maker, what controls the start of the ejection and refill cycle?

8. How can the original compact ice maker be manually turned off?

9. How many revolutions will the ejector blades of the original compact ice maker normally make during the ejection cycle?

10. What is the function of the holding switch in the original compact ice maker circuit?

11. Concerning the flex tray ice maker, what two separate tasks are performed by the timer motor?

12. What is the function of the spring loaded pin in the flex tray ice maker?

13. Concerning the flex tray ice maker, is it possible for the timer motor to operate during the defrost cycle?

14. Concerning the new type compact ice maker, what method is used to change the contacts labeled A, B, C, and D in the schematic diagram shown in figure 40-18?

15. Can the gear of the new type compact ice maker be rotated to manually advance the operation of the ice maker?

16. How many revolutions do the ejector blades of the new type compact ice maker make during the ejection cycle?

$ Chapter 41

1. Concerning the Scotsman cube-type ice maker, what device is used to cause the water to flow evenly over the surface of the evaporator plate?

2. Concerning the Scotsman cube-type ice maker, what method is used to thaw the surface of the ice in contact with the evaporator plate during the harvest cycle?

3. Concerning the Scotsman cube-type ice maker, what are the two safety switches used to disconnect power from the control circuit?

4. What device is used to sense the level of ice cubes in the storage bin of the Scots- man cube-type ice maker?

5. What electrical component starts the operation of the timer motor in the Scotsman cube-type ice maker?

6. Concerning the Scotsman flaker-type ice maker, what device is used to carry the ice to the top of the evaporator tube?

7. How is excess water pressed out of the ice before it is ejected into the storage bin of the flaker-type ice maker?

8. Explain the operation of the auger delay switch used in the flaker-type ice maker.

9. Concerning the flaker-type ice maker, why is it desirable to have the auger drive motor continue to operate for some period of time after the compressor has stopped operation?

10. What controls the operation of the bottom condenser fan motor in the flaker-type ice maker?

11. What electrical component is used to stop the operation of the compressor if the auger should become overloaded?

12. Concerning the Scotsman flaker-type ice maker, which safety switch must be manually reset if it trips?

$ Chapter 42

1. How many valence electrons are contained in a material used as a conductor?

2. How many valence electrons are contained in a material used as an insulator?

3. What are the two most common materials used to produce semi-conductor devices?

4. What is a lattice structure?

5. How is a P-type material made?

6. How is an N-type material made?

7. What type of semi-conductor material can withstand the greatest amourtt of heat?

8. All solid-state components are formed from combinations of P- and N-type materials. What factors determine what kind of components will be formed?

$ Chapter 43

1. What is the PN junction more commonly known as?

2. On a plastic case diode, how are the leads identified?

3. Explain how a diode operates.

4. Explain the difference between the conventional current flow theory and the electron flow theory.

5. Explain the difference between a half-wave rectifier and a full-wave rectifier.

6. Explain how to test a diode with an ohmmeter.

$ Chapter 44

1. Will the LED rectify an AC voltage into a DC voltage?

2. What is the average voltage drop of an LED?

3. How can the anode and cathode of an LED be identified?

4. What is the average amount of current permitted to flow through an LED?

5. Can LEDs be tested with most ohmmeters?

$ Chapter 45

1. What are the two basic types of transistors?

2. Explain how to test an NPN transistor with an ohmmeter.

3. Explain how to test a PNP transistor with an ohmmeter.

4. What polarity must be connected to the collector, base, and emitter of an NPN to make it forward t:iased?

5. What polarity must be connected to the collector, base, and emitter of a PNP transistor to make it forward biased?

6. Explain the difference between an analog device and a digital device.

$ Chapter 46

1. What do the letters UJT stand for?

2. How many layers of semi-conductor material are used to construct a UJT?

3. Briefly explain the operation of the UJT.

4. Draw the schematic symbol for the UJT.

5. Briefly explain how to test a UJT with an ohmmeter.

$ Chapter 47

1. What do the letters SCR stand for?

2. How many layers of semi-conductor material are joined to form an SCR?

3. SCRs are a member of what family of devices?

4. If an SCR is connected in an AC circuit, is the output AC or DC?

5. Is gate current used to turn the SCR on or off?

6. The amount of current flow through the anode-cathode section needed to keep an SCR turned on is called what?

7. When an SCR is connected in an AC circuit, what must be done to gain complete control of the output waveform?

8. What electronic component is generally used to phase shift an SCR?

$ Chapter 48

1. Briefly explain how a diac operates.

2. Draw the two schematic symbols for the diac.

3. What is the major use of the diac in industry?

4. When a diac fIrst turns on, does the voltage drop, remain at the same level, or increase to a higher level?

$ Chapter 49

1. Draw the schematic symbol of a triac.

2. When a triac is connected in an AC circuit, is the output AC or DC?

3. The triac is a member of what family of devices?

4. Briefly explain why a triac must be phase shifted.

5. What electronic component is frequently used to phase shift the triac?

6. When the triac is being tested with an ohmmeter, which other terminal should the gate be connected to if the ohmmeter is to indicate continuity?

$ Chapter 50

1. When the voltage connected to the inverting input is more positive than the voltage connected to the noninverting input, will the output be positive or negative?

2. What is the input impedance of a 741 operational amplifier?

3. What is the average open loop gain of the 741 operational amplifier?

4. What is the average output impedance of the 74l?

5. List the three common connections for operational amplifiers.

6. When the operational amplifier is connected as a voltage follower, it has a gain of one. If the input voltage does not get amplified, what does?

7. Name two effects of negative feedback.

8. Refer to figure 50-8. If resistor Rl is 200 ohms, the resistor R2 is 10K ohms, what is the gain of the amplifier?

9. Refer to figure 50-9. If resistor Rl is 470 ohms and resistor R2 is 47K ohms, what is the gain of the amplifier?

10. What is the purpose of the hysteresis loop when the op amp is used as an oscillator?