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60 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Flux is placed inside electrical solder in order to
A. clean the connections during soldering and prevent oxidation. B. raise the melting point of silver. C. increase the conductivity of the connection D. act as an insulator within the connection |
A. clean the connections during soldering and prevent oxidation.
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Flux is the component in solder that, when liquid, removes the impurities present in the connection and helps prevent oxidation. After it has cooled, the remaining flux present around or between connections acts as an insulator. Tin increases the conductivity of the connection, and it is the combination of tin and lead that results in the combined lower melting point for solder that is desired in electrical work.
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A cold solder connection is
A. clean and shiny in appearance. B. dull and brittle in appearance. C. a connection that is properly soldered. D. a connection achieved with a lowwattage iron. |
A. clean and shiny in appearance.
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A connection that is clean and shiny in appearance is an example of a properly soldered connection. The wattage of the iron used has no effect on the resulting solder connection. The soldering procedure determines what the connection will look like.
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A current reading of 1 mA is equivalent to
A. 0.1 ampere. B. 0.001 ampere. C. 1 ampere. D. 10 ampere. |
B. 0.001 ampere.
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1 ampere is equal to 1,000 mA.
0.1 ampere is equal to 100 mA. 0.01 ampere is equal to 10 mA. 0.001 ampere is equal to 1 mA. |
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An ohmmeter is used to check the condition of a fuse. If the fuse is good, the meter reading should be
A. 100K ohms. B. 120 volts. C. zero. D. infinity. |
C. zero.
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A good fuse will allow current to flow through it, or indicate continuity on a continuity check using an ohmmeter. If there is continuity, of if the fuse is good, the meter will read zero, or very low resistance.
Choices A and D indicate a resistance reading that is very high. |
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Which of the following metals has the highest conductivity?
A. silver B. copper C. aluminum D. zinc |
A. silver
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The material with the highest conductivity is silver, followed in order of conductivity by copper, aluminum, and zinc.
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Stranded wire is used in extension cords primarily because
A. it costs less than solid wire. B. it is flexible. C. it is a better conductor than solid wire. D. it is the only type of wire available in that gauge. |
B. it is flexible.
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Stranded wire and solid wire of the same gauge do not differ in conductivity. Both are available in numerous gauges, including the gauge used in extension cords. however, solid wire of the gauge needed for an extension cor is not nearly as flexible as stranded wire. Because an extension cord is often moved, stranded wire is preferable.
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A toaster is connected to 120 volts and draws 10 amperes when in use. How much power does this appliance consume?
A. 12 watts B. 120 watts C. 110 watts D. 1,200 watts |
D. 1,200 watts
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The formula to calculate power consumption is power = current • voltage, or P = I • E. Substituting the values given,
P = I • E P = 10 amperes • 120 volts P = 1,200 watts |
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How many cells does a 12-volt carbon-zinc car4 battery contain?
A. 12 B. 8 C. 6 D. 1 |
B. 8
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A carbon-zinc cell has a voltage of approximately 1.5 volts. In a 12-volt carbon-zinc battery there are 8 cells or 1.5 volts • 8 = 12 volts.
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The property of a circuit that opposes any charge in current is
A. inductance. B. capacitance. C. resistance D. reactance. |
A. inductance.
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The circuit property that opposes any change in current is defined as inductance. Capacitance is the circuit property that opposes any change in voltage. Resistance is the opposition to the flow of electrons, and reactance is the opposition to the flow of inductance or capacitance present in a circuit.
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Of the choices listed below, Which component is an example of a transducer?
A. resistor B. switch C. diode D. speaker |
D. speaker
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A transducer is a component that converts one form of energy ito another form of energy. A speaker converts the electrical energy at audio frequencies in the final stage of a radio receiver into sound energy. A resistor is used in a circuit to limit current flow and drop voltage or consume energy. A diode is used to block energy or rectify an AC signal, and a switch s a mechanical means of turning current on and off.
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The period of the sine wave is determined by
A. its amplitude. B. the distance between the crests of the wave. C. the number of hertz in 1 second. D. the time it takes to complete 1 hertz. |
D. the time it takes to complete 1 hertz.
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The time it takes to complete one sine wave is known as period of a wave. The distance between the crests of a wave is equal to 1 hertz, and the number of hertz completed in 1 second is known as the frequency. The amplitude of the wave is the distance between the ground line and the highest point of the wave in both the positive and the negative.
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What is the effective value of an AC signal of 141 volts peak value?
A. 141 volts B. 100 volts C. 120 volts D. 56.5 volts |
B. 100 volts
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The correct choice is B. To convert from AC peak value to AC effective value the formula is:
E(eff) = 0.707 • E(peak) E(eff) = 0.707 • 141 volts E(eff) = 100 volts |
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The frequency response of the human ear is in the range of
A. 16 to 16,000 Hz. B. 20,000 to 30,000 Hz. C. 50 KHz to 1 MHz. D. 1 MHz to 1000 MHz. |
A. 16 to 16,000 Hz.
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The term 'frequency response' is used to denote the range of frequencies that a device, or in this case the human ear, is sensitive to. Sound or audio frequencies fall into the range of 16 to 16,000 Hz.
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One kilowatt is equivalent to
A. 1 watt. B. 10 watt. C. 1,000 watt D. 1,000 volts. |
C. 1,000 watt
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The term 'kilo' represents a quantity of 1,000. Therefore 1 kilowatt is equal to 1,000 watts. Watts and voltage are not interchangeable terms. A watt is a unit of measurement of power, and a volt is a unit of measurement for voltage.
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What is the total resistance in this circuit?
Each resistor = 900 ohms A. 100 ohms B. 300 ohms C. 900 ohms D. 1,000 ohms |
B. 300 ohms
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The formula for parallel resistors is Rt = R/n, where 'R' is equal to the value of one resistor and 'n' is equal to the number of resistors that are of the same value in parallel. Substituting values into the equation:
Rt = (900/3) ohms Rt = 300 ohms |
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In the schematic of a DC power supply, an oscilloscope connected at points 'A' and 'B' would display what type of waveform?
A. square wave B. sine wave C. pulsating DC D. sawtooth wave |
C. pulsating DC
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The given schematic is of a full-wave DC power supply. At points 'A' and 'B' before the filter capacitor C1, the waveform is that of a pulsating direct current. A sine wave could not be displayed because a sine wave indicates a voltage that alternates between positive and negative values. At points 'A' and 'B' the voltage present has been rectified to full-wave direct current by the duo-diode tube. This resultant waveform is known as pulsating direct current. A sawtooth or square wave, although both are examples of pulsating direct current, are waveforms resulting from the introduction of other components after the rectification stage.
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Referring to the schematic picture, what is the purpose of Ca?
A. to bleed R1 B. to increase the output voltage C. to change the incoming A to DC. D. to filter the AC ripple voltage |
D. to filter the AC ripple voltage
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Capacitor 'C1' is used to smooth out the AC ripple voltage from the output of the power supply. Choice A is incorrect, as a resistor is used to bleed a capacitor, not vice versa. 1 is used as an output load resistor. R1 is used as an output load resistor. Choice B is incorrect because a capacitor cannot amplify, and choice C is incorrect because a capacitor cannot rectify a signal; that is the purpose of the duo-diode tube.
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Which is the correct schematic symbol for a tuning capacitor?
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Choices C and D are schematics of resistors. C is a fixed resistor. D is a potentiometer or variable resistor. Choice A is a fixed-capacitor symbol. In choice B the arrow through the fixed capacitor symbol denotes variability. As a tuning capacitor is a variable capacitor, this is the correct choice.
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What is the equivalent solid state component of the vacuum tube drawn above?
A. semiconductor rectifier B. silicon-controlled rectifier C. zener diode D. transistor |
D. transistor
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The schematic symbol drawn is of a triode tube. Its equivalent solid state component is the transistor. In the triode tube, the element plate, cathode, and grid correspond to the elements collector, emitter, and base, respectively, in the transistor.
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Which choice best describes the operation of the circuit drawn in the above schematic?
A. The lamp will light constantly when the switch is closed. B. The lamp will light only when the switch is open. C. The lamp will flash when the switch is closed. D. The lamp will not light with the switch open or closed. |
C. The lamp will flash when the switch is closed.
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When the switch is closed, the capacitor will charge through the resistor. When the voltage across the capacitor reaches the coltage necessary for the neon bulb to light, the lamp will glow. As the lamp glows, the capacitor discharges, resulting in a cycle of charge-discharge. This cycle will cause the neon bulb to flash.
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A 9-volt transistor contains how many cells?
A. one B. four C. six D. nine |
C. six
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A cell has a voltage of approximately 1.5 volts. A 9-volt battery therefore contains 6 cells, or 1.5 volts • 6 = 9 volts.
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Compared to a numb er 12 wire, a number 22 wire is
A. longer. B. shorter. C. larger in diameter. D. smaller in diameter. |
D. smaller in diameter.
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The higher the gauge number of a wire, the smaller its diameter.
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A resistor marked "1.5K Ω" has a value of
A. 1.5 ohms B. 105 ohms C. 1,500 ohms D. 1,500 watts |
C. 1,500 ohms
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The symbol K represents "kilo" or 1,000. A 1.5K-ohm resistor therefore has a value of 1.5 • 1,000 or 1,500 ohms. Choice D is incorrect because the unit of measurement of resistance is ohm. Watts is a unit of measurement for power.
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An equivalent term for electromotive force is
A. voltage. B. current. C. resistance. D. reactance. |
A. voltage.
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The interchangeable terms for voltage are electrical pressure, electromotive force, potential difference, difference of potential, and electrical force. The other choices are incorrect because they represent other circuit properties that cannot be substituted for the property of voltage.
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The property of a circuit that opposes any change in voltage is
A. conductance. B. capacitance. C. resistance. D. inductance |
B. capacitance.
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Capacitance can be defined as the circuit property that opposes any change in voltage. Inductance is the circuit property that opposes any change in current. Resistance is the circuit property that opposes the flow of electrons, and reactance is the opposition to the flow on an alternating current as a result of inductance or capacitance present in a circuit.
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The composition of 60/40 rosin core solder is
A. 60% lead, 40% tin. B. 60% tin, 40% lead. C. 60% silver, 40% rosin. D. 60% lead, 40% silver. |
B. 60% tin, 40% lead.
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Choice A has the quantities reversed, and choices C and D are incorrect because the mount of silver present in solder is minute, and rosin is a substance in the center of solder added to aid in the soldering process.
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A hair dryer is rated at 1,200 watts. Assuming it is operated at 120 volts, how much current will this appliance draw?
A. 10 amps B. 100 amps C. 1,000 amps D. 144,000 amps |
A. 10 amps
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To calculate the current requirement of an appliance, the power law can be applied
power = current • voltage P = I • E |
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Another term for cycles per second is
A. hertz. B. henry. C. kilo. D. mega. |
A. hertz.
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Henry is the unit of measurement for inductance. kilo represents a quantity of 1,000, and mega represents a quantity of 1 million.
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A crystal microphone is an example of what electrical phenomenon?
A. thermoionic emission B. piezoelectric effect C. inductance D. hysteresis |
B. piezoelectric effect
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The piezoelectric effect is the property of certain crystalline substances to change shape when a voltage is impressed upon them, as in the crystal microphone. Thermoionic emission is the escape of electrons from a surface because of the presence of heat. Inductance is the circuit property that opposes any change in current, and hysteresis is the property of a magnetic substance that causes magnetization to lag behind the force that produces it.
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The process of transmitting voice by varying the height of a carrier wave is known as
A. frequency modulation. B. amplitude modulation. C. demodulation. D. detection. |
B. amplitude modulation.
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The height of a waive is known as the wave's amplitude. Varying the height of a carrier wave is known as AM or amplitude modulation. Frequency modulation transmits intelligence by varying the frequency of the carrier wave. Demodulation is the process of separating the intelligence from the carrier wave. Another term for this process is detection.
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The primary of a transformer is connected to 120 volts. the voltage across the secondary is 40 volts. This transformer has a turns ratio of
A. 1:1 B. 1:4 C. 1:3 D. 3:1 |
D. 3:1
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The primary of this transformer has three times the voltage of its secondary. Therefore, the primary must have three times as many turns of wire as the secondary, or a turns of wire as the secondary, or a turns ratio of 3:1. If its turns ratio was 1:1, the primary and secondary would have the same voltage. In choice B, a turns ratio of 1:4 would result in an output voltage off 480 volts. in choice C a turns ratio of 1:3 would result in a secondary voltage of 360 volts.
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A carbon resistor marked with the color bands of red, red, red, gold is of what value and tolerance?
A. 2,000 ohms ± 5% B. 222 ohms ± 5% C. 2,200 ohms ± 5% D. 6 ohms ± 5% |
C. 2,200 ohms ± 5%
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Reading the resistor color code, the first two bans indicate numbers; the third band is the multiplier or the number of zeros to write after the first two numbers. The fourth band indicates the tolerance of the resistor. Following the color code, the value of this resistor is 2,200 ohms ± 5%. Red, representing a number value of 2 and a multiplier value of 100 (or two zeros to write after the first two numbers) would indicate a resistor coded as follows:
2/Band 1 - red 2/Band 2 - red 00/band 3 - red ± 5%/band 4 - gold The tolerance of a fixed carbon resistor is a ± value. Gold represents 5% tolerance. |
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Which is the correct schematic symbol of a tetrode tube?
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C. C is the correct schematic symbol of a tetrode tube.
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Choice A = diode; choice B = triode; choice D = pentode.
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What is the total resistance in this circuit if all resistors are 500 ohms?
A. 1,500 watts B. 1,500 ohms C. 1.5 ohms D. 500 ohms. |
B. 1,500 ohms
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In a series circuit, the total resistance is equal to the sum of the individual resistors, or Rt = R1 + R2 + R3 + ....+ Rn. As all resistors have a value of 500 ohms, the total resistance in this circuit is equal to
Rt = R1 + R2 + R3 Rt = 500 + 500 + 500 Rt = 1,500 ohms Choice A is incorrect because watts is a unit of power, not a unit of resistance. |
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The above schematic represents which transistor configuration?
A. common gate B. common collector C. common base D. common emitter |
C. common base
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he base element is common or shared by both circuits. choice A is not a transistor circuit configuration as there is no gate element in a transistor.
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which choice correctly identifies the waveform picture?
A. sine wave B. square wave C. sawtooth wave D. pure DC |
C. sawtooth wave
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The waveforms corresponding to the other choices are given in the review section on waveforms.
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Of the choices illustrated, which is the correct schematic symbol for a potentiometer?
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B. Choice B is the correct answer
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A potentiometer is a varriable resistor. Choice A is the symbol for a fixed resistor, and choice B is the symbol for a variable resistor; note the arrow connected to the fixed symbol. Choice C is a fixed capacitor, and choice D is the symbol for a variable capacitor.
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A component on a parts list has the following specifications, "1µF, 50 wvdc." The component specified is a
A. potentiometer. B. coil. C. transistor. D. capacitor. |
D. capacitor.
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The unit of measurement for capacitance is the farad, abbreviated F. A potentiometer would be specified in ohms, a coil in henrys, and a transistor by its type or generic number.
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the illustration is a block diagram of a transmitter and receiver. What is the purpose of the oscillator?
A. to generate a radio frequency B. to produce a carrier wave for the intelligence C. to produce a high-frequency current D. all of the above choices. |
D. all of the above choices.
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The purpose of the local oscillator is to generate a high frequency, also known as a radio or carrier wave.
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Referring to the schematic above, what is the purpose of the detector stage?
A. to amplify the audio signal B. to tune in the carrier wave C. to separate the audio from the radio wave D. to amplify the radio frequency |
C. to separate the audio from the radio wave
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A detector demodulates a signal. This is the process of separating the audio or intelligence from the radio wave. An AF amp is used to amplify the audio signal, and the RF amp is used to amplify the radio frequency. A turner is used to tune in a frequency, making choices A, B, and D incorrect.
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Which of the following causes the inductance of a coil to decrease?
A. a copper core B. an iron core C. more turns of wire D. shortening the length of the coil |
A. a copper core
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When copper is inserted inside a coil, it makes the inductance decrease.
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Permeability is
A. a unit of measurement of magnetism. B. a force field intensity measurement. C. the case with which magnetic lines of force distribute themselves throughout a material. D. a property of a permanent magnet. |
C. the case with which magnetic lines of force
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Permeability is the ease with which magnetic lines of force distribute themselves throughout a material.
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Which of the following is not a factor in determining capacitance of capacitor?
A. area of the plates B. distance between the plates C. material used as a dielectric D. voltage applied to the plates |
D. voltage applied to the plates
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The area of the plates, the distance between the plates, and the material of the dielectric all have a direct relationship on the capacitance of a capacitor. The voltage on the capacitor does not have an effect on its capacitance.
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Capacitors placed in series produce
A. less capacitance. B. a lower WVDC rating. C. more capacitance. D. higher reliability. |
A. less capacitance.
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When capacitors are placed in series, it is the same as placing the plates farther apart. This causes a decrease in the amount of capacitance for the series combination.
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'XC' is ecual to
A. (1/2) π • FC B. (1/2) π • FL C. 2π • FL D. 2π • FC |
A. (1/2) π • FC
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Capacitive reactance is equal to the reciprocal of the product of 2π • FC.
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Capacitors connected in parallel
A. produce more capacitance. B. produce less capacitance. C. produce a higher WVDC rating. D. handle more voltage. |
A. produce more capacitance.
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Capacitors connected in paralll effectively increase the plate area. That allows for more storage of electrons and more capacity or capacitance.
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Impedance (Z) of a series RL circuit can be found by using
A. Z = √R² + Xc² B. Z = √R² + Xl² C. Z = √R + Xl D. Z = √R + Xl² |
B. Z = √R² + Xl²
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The impedance of a series RL circuit can be found by taking the square root of the sum of the squares of the resistance and the inductance. The inductance is in henry's and the resistance is in ohms.
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Parallel resonance occurs in a circuit when
A. Z = Xl B. Z = Xc C. X = 2π • FC D. Xl = Xc |
D. Xl = Xc
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Resonance occurs in any circuit then the inductive reactance and the capacitive reactance are equal.
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A filter is used in a power supply to
A. change AC to DC. B. change DC to AC. C. smooth out voltage variations. D. smooth out power surges. |
C. smooth out voltage variations.
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A filter is placed in the power supply to smooth out the voltage variations. In some cases a choke is used in the filter to smooth out the current variations.
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Another name for a transistor is
A. diode. B. semiconductor. C. crystal amplifier D. integrated circuit. |
C. crystal amplifier
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Another name for the transistor is the 'crystal amplifier'. It has also been called the 'transfer resistor', from which it takes its name, 'transistor'.
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Radio frequency amplifiers are used in
A. audio amplifiers. B. differential amplifiers. C. operational amplifiers. D. receivers and transmitters. |
D. receivers and transmitters.
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Radio frequency simplifiers are used in receivers and transmitters to amplfy frequencies above the human hearing range.
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A crystal microphone uses
A. the piezoelectric effect. B. the pressure pack effect. C. magnetic wves to operate. D. a permanent magnet to operate. |
A. the piezoelectric effect.
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A crystal microphone relies on the piezoelectric effect, where a pressure on a crystal produces an electric current.
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The voice coil of a speaker has an empedance that is
A. high. B. low. C. made of ceramic materials. D. made of ferrite materials. |
B. low.
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The voice coil of a speaker usually has a very low impedance. Some especially made speakers have higher impedances to match the system.
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A crossover network is used to
A. direct the proper frequency range to the right speaker. B. eliminate noise. C. filter out high frequencies. D. filter out low frequencies. |
A. direct the proper frequency range to the right speaker.
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A crossover network is designet to make sure that the right frequencies get to a speaker so it can produce them better.
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The klystron is used in
A. low-frequancy transmitters. B. radar units. C. audio frequency amplifiers. D. frequency detectors. |
B. radar units.
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The clystron is used as a frequency source in microwave units - whether it can be a microwave range for the kitchen or a radar unit of an aircraft.
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There are two basic types of oscillators used for microwave generation. They are magnetron and the
A. klystron. B. op amp. C. Clapp oscillator D. multivibrator. |
A. klystron.
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The two basic types of oscillators used in microwave installations are the klystron and the magnetron.
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There are two types of diode used in electronic work. They are semiconductor diode and the
A. vacuum tube diode. B. full-wave diode. C. half-wave diode. D. zener diode. |
A. vacuum tube diode.
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The two general types of diodes are the semiconductor and the vacuum tube diode. Both types have particular applications and advantages.
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Color television relies on three colors to produce the full color range needed for a good picture.
These colors are red, blue, and A. grey. B. orange. C. yelow. D. green. |
D. green.
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Color television uses red, blue, and green guns to direct electron streams toward the phosphoris in the front of the picture tube. They produce the full-color spectrum when combined properly.
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The folded dipole antenna has an impedance of
A. 72 ohms. B. 300 ohms. C. 600 ohms. D. 75 ohms. |
B. 300 ohms.
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The folded dipole antenna has an ipedance of 300 ohms. It is the one most commonly used for home television reception. The dipole has an impedance of 72 ohms.
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Television sets in the United States are a horizontal frequency of
A. 525 hertz. B. 60 hertz. C. 15,750 hertz. D. 15,625 hertz. |
C. 15,750 hertz.
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Television sets in the United States use a horizontal frequency of 15,750 Hz, while those in Europe use 15,625 Hz. There are 525 lines that make up the television picture in the United States, but 625 in Europe. The vertical oscillator freequency is 60 Hz in the United States, but 50 in Europe.
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