Chapter 3: Electricity, Components, and Circuits Flashcards
Electrical current is measured in what unit?
Amperes, amps, or A
What is the name for the flow of electrons in an electric circuit?
Current, or I
What is the name for a current that flows only in one direction?
Direct Current or DC
What is the electrical term for the electromotive force (EMF) that causes electron flow?
Voltage, Volts, or E
What is the name for a current that reverses direction on a regular basis?
Alternating Current, or AC
What is the unit of electromotive force?
Volts, or V
Which instrument would you use to measure electric potential or electromotive force?
Voltmeter, or Multimeter
Which instrument is used to measure electric current?
Ammeter, or Multimeter
In which type of circuit is current the same through all components?
Series circuit
In which type of circuit is voltage the same across all components?
Parallel circuit
What happens to current at the junction of two components in series?
The same current flows in each components
What happens to current at the function of two components in parallel?
When components are connected in parallel with a source of voltage, the voltage across each is the same as that of the source.
What is the voltage across each of two components in series with a voltage source?
When the components are connected in series with the source voltage, the voltage divides between the components, depending on their type and value
What is the voltage across each of two components in parallel with a voltage source?
The voltage divides between the components, depending on their type and value
What is the correct way to connect a voltmeter to a circuit?
Voltmeters are connected in parallel with or “across” a component or circuit to measure voltage
How is a simple ammeter connected to a circuit?
Ammeters are connected in series with a component or circuit to measure current
Which of the follow is a good electrical conductor?
Copper
Which of the following is a good electrical insulator?
Glass, ceramics, dry wood, paper, most plastics, other non-metals
What instrument is used to measure resistance?
Ohmmeter, or Multimeter
What formula is used to calculate current in a circuit?
I = E / R
What formula is used to calculate voltage in a circuit?
E= I x R
What formula is used to calculate resistance in a circuit?
R = E / I
Electrical power is measured in which of the following units?
Power is measured in Watts, or W
Which term describes the rate at which electrical energy is used?
Power, represented by P
What is the formula used to calculate electrical power in a DC circuit?
The product of voltage and current (P = E x I)
What is the ability to store energy in an electric field called?
Capacitance, measured in faraday (F)
What is the ability to store energy in a magnetic field called?
Inductance, measured in Henry’s (H)
What electrical component opposes the flow of current in a DC circuit?
Resistors
What type of component is often used as an adjustable volume control?
Potentiometer
What electrical parameter is controlled by a potentiometer?
Adjusts voltage or potential
What electrical component stores energy in an electric field?
Capacitors
What type of electrical component consists of two or more conductive surfaces separated by an insulator?
Capacitors
What type of electrical component stores energy in a magnetic field?
Inductors
What electrical component usually is constructed as a coil of wire?
Inductors
What component is commonly used to change 120V AC house current to a lower AC voltage for other uses?
Transformer
What is impedance?
A general term to mean the circuit’s opposition to AC current flow, a combination of resistance and reactance, measured in Ohms
Which of the following is combined with an inductor to make a tuned circuit?
A capacitor is combined with an inductor to make a tuned circuit
What is the main purpose of a resonant or tuned circuit?
A tuned circuit acts as a filter, passing or rejecting signals at its resonant frequency.
What class of electronic component uses a voltage or current signal to control current flow?
Transistors
What electronic component allows current to flow in only one direction?
A Semiconductor
Which component can be used as an electronic switch or amplifier?
With an appropriate external circuit and a source of power, transistors can amplify or switch voltages and currents
Which component can consist of three layers of semiconductor material?
Transistors
Which electronic component can amplify signals?
Transistors
How is the cathode lead of a semiconductor diode often marked on a package?
By a stripe mark
What does the abbreviation LED stand for?
Light Emitting Diode
What does the abbreviation FET stand for?
Field-Effect Transistors
What does BJT stand for?
Bipolar Junction Transistors
What are the names of the two electrodes of a diode?
Anode and Cathode
Which of the following could be the primary gain-producing component in an RF power amplified?
RF power transistors
What is the term that describes a device’s ability to amplify a signal?
Using small signals to control or amplify larger signals is called gain
Which of the following devices or circuits changes an alternating current into a varying direct current signal?
Diode
Which of the following is commonly used as a visual indicator?
LEDs
What is the name of a device that combines several semiconductors and other components into one package?
Integrated Circuit (IC or chip)
What electrical component is used to protect other circuit components from current overloads?
Fuses and circuit breakers
What is the purpose of a fuse in an electrical circuit?
What the metal melts, or “blows”, the current path is broken and power is removed from circuits supplied by the fuse.
Why is it unwise to install a 20-ampere fuse in the place of a 5-ampere fuse?
Using one with a higher current rating, even temporarily, could allow the fault to permanently damage the equipment or start a fire.
What electrical component is used to connect or disconnect electrical circuits?
Switches and relays control current through a circuit
What is a relay?
A relay is a switch controlled by an electromagnet
What is the name of an electrical wiring diagram that uses standard component symbols?
Schematics
What do the symbols on an electrical schematic represent?
Visual description of a circuit and its components that uses standardized drawings called circuit symbols.
Which of the following is accurately represented in electrical schematics?
Each line indicates that an electrical connection exists between the component at the end of the line.
What is the name of a circuit that generates a signal at a specific frequency?
An oscillator
Which of the following describes combining speech with an RF carrier signal?
Modulation
Which of the following is used to convert a radio signal from one frequency to another?
A mixer, combines two RF signals and shifts one of them to a third frequency
Which of the following might damage a multimeter?
Trying to measure voltage or connecting the probes to an energized circuit when the meter is set to measure resistance
Which of the following measurements are commonly made using a multimeter?
All three electrical values of voltage, current and resistance.
What is probably happening when an oh meter, connected across an unpowered circuit, initially indicates a low resistance and then shows increasing resistance with time?
Indicates the presence of a large-value capacitor.
Which of the following precautions should be taken when measuring high voltages with a voltmeter?
Ensure the voltmeter and leads are rated for use at the voltages to be measured.
Which of the following displays an electrical quantity as a numeric value?
A meter provides information as a value in the form of numbers or on a numeric scale.
