17. Electronics Information Flashcards
What is electricity?
Electricity is a general term for the variety of phenomena resulting from the presence and flow of electric current.
Electricity is measured in three ways, what are those? synthesize.
- Volts: Volts measure the difference of potential between two points.
- Amperes (amps): Amps measure the number of electrons that move past a specific point in 1 second.
- Ohms: Ohms measure resistance, including anything that could limit the flow of electrons.
Synthesize the following terms: Current, Watt, Watt-hour, Kilowatt and kilowatt-hours, Megawatt, and Megawatt.
- Current: Electricity is like water — it flows. Electrical current occurs when electrons move from one place to another. The use of conductors, such as copper and water, allows the electrons to move freely. Insulators, such as rubber and wood, discourage the electric current.
- Watt: A watt measures power, the rate at which electrical energy is consumed or transformed into another type of energy, such as light or heat.
- Watt-hour: A watt-hour is the amount of energy used in 1 hour at a rate of 1 watt. Most electricity is measured in kilowatt-hours, which is how much energy you’d use if you ran a 1,000-watt (1-kilowatt) device for an hour. For example, 10 kilowatt-hours is enough energy to run a 10,000-watt speaker system for an hour-long outdoor concert, or it could run a 5,000-watt air conditioner for 2 hours or a 1,000-watt waffle iron for 10 hours. You find watt-hours by multiplying wattage by time (expressed in hours).
- Kilowatt and kilowatt-hours: One kilowatt (kW) equals 1,000 watts, and one kilowatt-hour (kWh) is one hour using electricity at a rate of 1,000 watts. Kilowatt-hours are what you see on your electricity bill; they’re useful for measuring large amounts of electricity.
- Megawatt: Megawatts (MW) are tremendous. One megawatt is equal to 1,000 kilowatts (and 1,000,000 watts). This unit measures things like power plants or how much electricity an entire city uses.
- Gigawatt: Gigawatts (GW) measure the capacity of large power plants (or multiple smaller power plants). One gigawatt is equal to 1,000 megawatts and 1 billion watts. (Rumor has it that 1.21 gigawatts can power a time machine).
What is the valence shell?
Valence shell is the number of electrons in the outer shell of an atom, and it determines whether an element is a conductor, semiconductor, or insulator.
What is the difference between conductors, semiconductors, and insulators?
- Conductors allows electrons to flow freely between different atoms. these valence shells have more empty spots than they have electrons.
- Semiconductors have half-full valence shells (or half-empty, depending on your attitude) and are neither good conductors nor good insulators.
- Insulators have pretty full valence shells (at least more than half), so electrons can’t move much (or at all) between atoms. They’re very poor conductors.
What is an electrical current?
Electric current is the flow — or, more precisely, the rate of flow — of electrons in a conductor. Electrons carry an electrical charge that is expressed in coulombs (C).
If 1 Coulomb flows past a specified point in 1 second, that’s a flow rate of 1 ampere.
What is an ampere?
An ampere represents the movement (flow) of electrons, so electrical currents are measured in amps. Typically, current is tiny, so small that it’s measured in milliamperes; 1 milliampere is one-thousandth of an ampere. Current meters, called ammeters, measure the flow of current through a circuit. You can compare the flow of electrons to water coming from a garden hose; amps are equivalent to gallons-per-minute if you are washing your car in the driveway.
What is a circuit breaker?
Sometimes a circuit must be opened in order to add or remove resistance. In other words, the flow of the electricity must be interrupted in order to physically change the resistance. Using a circuit breaker, which is a device that automatically interrupts the electrical current, is an example of opening a circuit control the current. When the circuit breaker trips, the electrical device can no longer operate.
What is a rheostat?
Some devices use a rheostat, which can vary the resistance without opening the circuit — the device can continue to work even as the resistance is altered. If an application doesn’t use all the electricity, the rheostat absorbs it. A dimmer switch on a light is an example of a rheostat. You increase the amount of resistance to dim the light and decrease the resistance to brighten the light.
If you have a current flowing through a wire, three influences are present, what are those?
- The amount of voltage, measured in volts (V) or electromotive force (EMF).
- The resistance to the current, measured in ohms (Ω).
- The amount of current, measured in amperes and expressed as I or i
What is the definition of the word Ohms? & What is Ohms law?
The amount of resistance that interferes with the flow is measured in ohms (pronounced just like those yoga chants).
Ohm’s law, which was first stated by Georg Simon Ohm, reads, “The current in a circuit is directly proportional to the applied voltage and inversely proportional to the circuit resistance,” but it’s actually easier to understand in mathematical terms. When stating the relationship mathematically, abbreviations are used, where I is current, V is voltage, and R is resistance:
Current (amperes) = Voltage (volts)/Resistance (ohms), or I=V/R
What is voltage?
Voltage is the difference of the pressure between two points in a circuit. It’s sometimes called the voltage drop or difference of potential.
In electronics, what is the term ground?
Ground is any part of a circuit (or other object that has electricity running through it) that measures 0 volts, such as the case of your radio, the base of a lamp, or the chassis of your car. The negative terminal of 9-volt battery is at ground potential, so the voltage from the negative terminal of the matter measures 9 volts.
How can you measure the voltage in a circuit?
You might need to use a voltmeter or a multimeter, which has several meters in one instrument. A voltmeter has two leads. To measure voltage, you place one lead somewhere in the circuit and one lead at another location in the circuit. The voltmeter tells you what the voltage is between those two points.
What is a cell?
A cell is a storage compartment for electricity in a battery, in which it has a specific voltage. For example, in a particular battery, cells may be 1-5 volts. Therefore, you can figure out the number of cells that battery has by dividing the voltage of the battery by 1.5.
Name each symbol in electronic circuit diagrams and set forth its function when connected in a circuit.
Wires: Wires are used to pass current from one part of the component to another. Wires that are connected to each other are indicated by a dark circle and are called joined wires. Sometimes in complex circuit diagrams, it’s necessary to draw wires crossing even though they aren’t connected. In this case, the dark circle is omitted, or hump symbol is drawn to make it clear the wires aren’t connected — these are called unjointed wires.
Cell: A cell supplies electrical current. Some call this a battery, but technically a battery is more than one cell. The large terminal (on the left side of the cell image) is positive.
Battery: A battery is two or more cells. The large terminal is positive.
DC power supply: A DC power supply provides direct current. Direct current always flows in one direction.
AC power supply: An AC power supply provides alternating current. Alternating current constantly changes direction at a specific frequency.
Fuse: A fuse is a safety device that blows (melt) if the current flowing through it exceeds a specified value.
Transformer: A transformer consists of two coils of wire linked by an iron core. Transformers are used to step up (increase) and step down (decrease) AC voltages. No electrical connection exists between the coils. Energy is transferred between the coils by the magnetic field in the core.
Ground: A ground is a connection to the Earth.
Transducer: A transducer is a device that converts energy from one form to another. Here are various types of transducers:
- Lighting lamp: Converts electrical energy to light, such as in a light bulb or automobile headlight
- Indicator lamp: Converts electrical energy to light for such uses as a warning light on a car’s dashboard.
- Motor: Converts electrical energy to kinetic energy (motion)
- Heater: Converts electrical energy to heat.
- Bells and buzzers: Convert electrical energy to sound.
- Microphone: Converts sound to electrical energy.
- Earphones and speakers: Convert electrical energy to sound.
Inductor: An inductor is a coil of wire that creates a magnetic field when current passes through it.
Switch: Here are several types of switches:
- Push switch: A push switch allows current to flow only when the button is pressed, such as in a doorbell.
- Push-to-break switch: With this switch, the circuit is normally closed (the device is on); the circuit is open (device is off) only when the button is pressed.
- On/off switch: An on/off switch allows current to flow only when it’s in the closed (on) position.
- Two-way switch: A two-way switch directs the flow of current to one of two routes, according to its position.
- Dual on/off switch: This type is often used to switch main electricity because it can isolate both the live and neutral connections.
- Relay (relay switch): A relay is an electrically operated switch that may operate multiple switches at one time. Typically, a small current flowing through a coil sets up a magnetic field, which causes the lever(s) to move, effectively changing the (relay) switch’s position(s). As an example, a 5-volt signal from your dashboard turns on your 12-volt headlights through a relay.
Resistor (nonvariable): There are two different versions of the basic resistor symbol. Resistors restrict the flow of electric current. Resistors are rated in ohms and have a color code on them to indicate their value, tolerance, and sometimes quality. The band code is as follows:
- Black is 0
- Brown is 1
- Red is 2
- Orange is 3
- Yellow is 4
- Green is 5
- Blue is 6
- Violet is 7
- Gray is 8
- White is 9
The first and second bands on the resistor are the first two digits in the resistor’s value. The next band indicates the multiplier (number of zeros after the first two numbers). So, if the first band is red, the second is yellow, and the third band is orange, the resistor’s value is 24,000 ohms, A gold or silver band after the first bands indicates tolerance, and a quality band may follow the tolerance band.
Variable resistor: Variable resistors also restrict the flow of electric current. There are several symbols in use in circuit diagrams for standard variable and preset variable resistors. Types of variable resistors include the following
- Rheostat: A type of variable resistor with two contacts, usually to control current; examples of controlling current would be adjusting lamp brightness or adjusting motor speed.
- Potentiometer: A type f variable resistor with three contacts that’s used to control voltage.
- Preset variable resistor: A device that operates with a small screwdriver or similar tool; it’s designed to be set when the circuit is made and then left without further adjustment.
Capacitor: Capacitor store electric charge. They’re used with resistors in timing circuits because it takes time for a capacitor to with charge. They’re also used in filter circuits because capacitors easily pass AC (changing voltage) signals but they block DC (constant voltage) signals. Two types of capacitors include the following:
- Polarized capacitors must be connected the correct way in circuit.
- Variable capacitors are used most often in radio tuning circuits.
Diode: Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve, and early diodes were actually called valves. Light-emitting diodes (LEDs) emit light when an electric current passes through them. Specialized diodes, called Zener diodes, do allow current in the opposite direction after a threshold. is met.
Transistor: Transistors amplify current. For example, they can be used to amplify the small output current from a logic chip so it can operate a lamp, relay, or other high-current device.
Amplifier: An amplifier isn’t actually an electronic component but instead is a complex circuit. The block diagram symbol shows where an amplifier circuit would be connected. Amplifier circuits are used to magnify power, current, or voltage.
Antenna: An antenna is a device designed to receive and/or transmit radio signals.
