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3E051 Set C Book 2
| Question | Answer |
|---|---|
| We call anything that has weight and occupies space | matter |
| Scientists can combine elements in either | compounds or mixtures |
| According to the elctron theory, atoms are composed of | protons, neutrons and electrons |
| Which statement best describes a positive ion? | an atom that lost an electron and has more protons |
| What effect of current causes an electric motor to produce mechanical energy? | Magnetism |
| Which of there is the smallest current that can be fatal under certain conditions? | one-tenth of 1 amp |
| What moves a sufficient number of electrons to perform a useful job? | voltage |
| A thermocouple produces voltage as a result of what type of energy? | Heat |
| According to Ohm's law, how much voltage is needed to push 1 ampere of current through 1 ohm of resistance? | 1 volt |
| What normally causes the resistance of a conductor to increase? | increase in temperature |
| What is the unit of measurement for electrical power? | watts |
| A 3-horsepower motor consumes how much power? | 2.238 kW |
| We call a magnet that is magnetized by induction from an external source | an artificial magnet |
| You can create a polarity and increase the strength of the magnetic lines of force around a conductor by | looping the conductor into a coil |
| What items are required to construct an electromagnet? | a coil of wire, a core material, and current flow |
| What are the two most common methods of producing voltage? | chemical and mechanical |
| What are the three things needed to produce voltage by the principle of eletromagnetic induction? | magnetic field, a conductor and relative motion |
| What type of current flow is the result of voltages produced by batteries and thermocouples? | Direct current |
| What type of current flow cannot be transformed from a higher voltage to a lower voltage? | Direct current |
| Which formula for finding the resistance of a circuit is correct? | voltage divided by current |
| What is the resistance of a circuit with an applied voltage of 120 volts and a curent flow of 9 amperes? | 13.33 ohms |
| How much current flow is in a circuit that has 24 volts applied and 72-ohms of resistance? | 0.33 amperes |
| What is the current flow in a series circuit with a 20-ohm resistor, a 25-ohm resistor, and a 30-ohm resistor connected to a 25-volt power supply? | 0.33 amperes |
| The total current in a parallel circuit is equal to the | sum of the currents in the individual branches |
| The joint resistance of a parallel circuit is equal to the applied voltage divided by the | total current |
| What is the joint resistance of a 5-ohm resistor and a 20-ohm resistor in parallel? | 4 ohms |
| What is the joint resistance of a 4-ohm resistor, a 10-ohm resistor and a 12-ohm resistor in parallel? | 2.3 ohms |
| What is the current flow in amperes of a circuit with an applied voltage of 120 volts and a power consumption of 600 volts? | 5 amperes |
| What is the power in watts consumed by a circuit with 120 volts applied and a resistance of 12 ohms? | 1200 watts |
| How many watts of power are present in a 5-ohm unit of resistance through which 2 amperes are flowing? | 20 watts |
| How many rotations per minute (rpm) must a 2-pole generator rotate to produce 60 Hz? | 3,600 rpm |
| What do we call the actual rating of alternating current (AC) power that is available to do work? | effective value |
| How do we express the measurement of the apparent power of an alternating current (AC) electrical system? | Kilovolt-amperes |
| What unit of measurement do we use in calculating the induction of a coil? | Henry |
| Which formula do we use to calculate impedance in an alternating current (AC) circuit? | Z=E/I |
| What is the capacitance of a 125 microfarad capacitor when we convert it to farads? | 0.000125 F |
| The rules and equations for direct current (DC) circuits apply to alternating current (AC) circuits having | only resistive load elements |
| Kirchoff's voltage law states that | the algebraic sum around a closed loop must equal zero. |
| In an alternating current (AC) circuit, when current and voltage are out of phase, true power is | less than apparent power |
| A 110-volt alternating current (AC) motor records 20 in-line amperes, and the in-line wattmeter shows only 1,936 watts being consumed. What would be the power factor of the AC circuit? | 88 percent pf |
| What type of generator has brushes riding on the commutator to carry the current to an external circuit? | DC circuit |
| What is the advantage of a having rotating magnetic field alternator? | the output is taken from the stationary stator coils |
| A three-phase alternator normally receives power for its rotating magnetic field from | a direct current (DC) generator |
| The voltage of a primary cell depends on the type of | electolyte and the electrode material |
| A step-up transformer produced a secondary voltage that is | higher and secondary current that is lower than the voltage and current in the primary |
| What does the word electronics mean? | the control of electrons in motion |
| An electron is considered a free electron when it reaches the | conduction band |
| A positive mobile charge is considered a | hole |
| What determines whether an element is a conductor, an insulator or a semiconductor? | the width of the forbidden band |
| External heat applied to electronic components | causes increased current flow |
| Which condition exists when you connect the negative battery lead to a cathode? | forward bias |
| Which of the following shows a proper electronic relationship? | anode/p-type material |
| Which device should only be used in direct current (DC) circuits? | Electrolytic capacitors |
| What does the tapered side on some diodes indicate? | cathode |
| Which meter connection do we use to read forward bias on a diode? | black lead to cathode |
| What does the arrow on electronic components indicate? | The direction of hole current |
| What is a zener diode typically used for? | voltage regulation |
| What is the key to the silicon controlled rectifier's (SCR) operation? | gate |
| How do we label the electrodes on a transistors? | Emitter, base, and collector |
| Which of the following are types of transistors? | NPN and PNP |
| How does the base of a transistor normally recieve its control voltage? | voltage divider circuit |
| In how many configurations can we connect transistors? | three |
| What controls the conduction time of a silicon controlled rectifier (SCR)? | gate current |
| What components make up a voltage divider circuit? | resistors in series |
| Which component protects a silicon controlled rectifier (SCR) gate from reverse voltage? | Diode |
| How do you turn off a silicon controlled rectifier (SCR) in a minimum amount of time? | apply reverse bias to the anode |
| The five major classes of integrated circuit components are direct logic (DL), transistor-transistor logic (TTL), | RTL, DTL, and DCTL |
| Both discrete and integrated seiconductor operations share the common problem of | faulty connections |
| Which of the following is a logic gate? | AND |
| Which of the following is not a logic gate? | STOP |
| The load resistor of a half-wave rectifier serves two purposes-to develop the output signal and to | limit current flow to a safe level |
| A full wave rectifier can be identified easily because it contains | a center-tapped transformer |
| The breakdown rating for diodes in a full-wave rectifier must be twice as great as the | half-wave rectifier |
| The average output voltage level of a bridge rectifier is equal to 0.636 | peak input voltage |
| The output ripple frequency (pps) of a three-phase bridge rectifier is how many times the input frequency | 6 times |
| The output of a three-phase rectifier is of low amplitude and requires | little filtering |
| In a circuit powered by a rectifier, why does a ripple voltage exist? | the rectifier supplies energy in pulses |
| An inductive (choke) input filter gives a lower output voltage than the capacitive input LC filter and also provides | better voltage regulator |
| Which statement describes the characteristics of the Pi-type LC filter in comparison to the RC pi-type filter? | High-output voltage and better voltage regulation |
| In the common emitter configuration, the input is between the emitter and base, and the output is between the | collector and emitter |
| If we apply the positive alternation of an input signal to the base of an NPN transistor in a common emitter configuration, what does it cause? | an increase in base current |
| The controlling element element in a common base configuration is the | emitter |
| Which gain characteristic of a common base transistor amplifier is less than 1? | current |
| Input resistance to a common collector amplifier is high because the emitter signal opposes the | base signal |
| What purpose does the zener diode in the elctronic voltage regulator serve? | sets the reference voltage |
| The output voltage of the electronic voltage regulator circuit | can be adjusted to a specific value |
| What are the most common frequencies for transmission of electrical power? | 50 Hz, 60 Hz, 400 Hz |
| One effect of high harmonic levels is | misoperation of sensitive electronis |
| Which three pieces of equipment do we use most often to measure harmonics? | wave analyzers, oscilloscope, spectrum analyzers |
| Which piece of equipment gives immediate qualitative information on the degree and type of distortion? | oscilloscope |
Created by:
melissafish
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