Electricity

what is the speed of light?

3 * 10⁸ m/s 186,000 miles/second

capacitor lightning analogy

Even nature shows the capacitor at work in the form of lightning. One plate is the cloud, the other plate is the ground and the lightning is the charge releasing between these two "plates." Obviously, in a capacitor that large, you can hold a huge amount of charge!

holding contacts

Holding contacts are normally opened contacts controlled by the energization of the relay coil. When the cct is energized they are closed If they are wired in parallel with a momentary contact button then when the button is pushed, the relay coil energizes, and the contacts close effectively "holding" the circuit from opening when the pushbutton is released.

MOSFET

Metal Oxide Semiconductor Field Effect Transistor. It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals.

2-phase electricity

Two-phase electrical power was an early 20th-century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by one-quarter of a cycle, 90°. Usually circuits used four wires, two for each phase.

how to find the voltage of a fully rectified sine wave?

V = peak * .637 V = RMS * .9

volt-ampere (VA)

apparent power applied voltage * total current

voltaic cell

constructed by using almost any 2 unlike metals and an acid, alkaline, or salt solution

inductive reactance (XL)

countervoltage produced by current flowing through an inductor. the induced voltage is 180° out of phase with applied voltage

leakage current

electrons that sneak past the dielectric plate in a capacitor

The process of depositing a thin layer of metal on an object during electrolysis. Common use for electroplating is for the production of pure metals -the electrolyte solution must contain ions of the metal being plated -metal ions are always positively charged -the object being plated must be connected to the cathode -DC must be the power source -the anode must be made of the same material used for the coating

electroplating

energy density

energy value of a substance given its volume

hydrometer

device used to measure specific gravity

Solar Cell

photovoltaic cell composed of P & N type semiconductors. Light is composed of photons which have pure energy and essentially no mass. When a photon hits a photocell the energy in the photon is transferred to a free electron. The additional energy the electron receives allows it to cross the junction between the 2 semiconductors to produce a voltage. Current produced by a solar cell is based off the surface area

full-wave rectification

positive and negative portions of the AC wave are turned into DC

hole current

positive to negative flow used by engineers. instead of talking about valence electrons hopping atom to atom, they invert it and say the stable atoms move. essentially just do this so there equations aren't always negative

capacitor uses

power factor correction, storing electric charge to create a large current pulse, timing circuits, electronic filters, start/run motors.

scalars

quantities that have only a magnitude (do not include direction)

Passivation

the process of treating or coating a metal in order to reduce the chemical reactivity of its surface. In stainless steel, passivation means removing the free iron from the surface of the metal using an acid solution to prevent rust.

induction

the production of an electric current in a conductor by varying the magnetic field applied to the conductor

what is a holding contact wired in parallel with?

the start push button

dielectric stress

the stretching of the valence orbits due to the potential between the positive and negative plate. the amount of stress is proportional to the voltage difference between the plates

thermopile

thermocouples connected in series to obtain a higher voltage

when can true power (watts) only be created?

true power or watts can only be produced when voltage and current are both positive or both negative. This is why a pure inductive circuit doesn't produce any power.

ampere-hour rating

used to rate batteries. its based off a batteries ability to produce current for an 20 hour period at 80°F. A battery that can produce 4A for 20 hours has an 80 ampere-hour rating

AC electrolytic capacitor

uses the electrolytic wet-type capacitors splitting and reforming qualities to its advantage. used as the starting/run capacitor on motors. it is made by connecting 2 wet capacitors together.

electrical bank

many wires connected into one point

60Hz

means the voltage rises to its maximum value, back to zero, to its lowest value, and back to zero 60 times in one second.

Power factor (PF)

ratio of true power to apparent power. measure of electrical efficiency

oil filled paper capacitor

often used as the run or starting capacitor in motor circuits and for power factor correction. made by separating plates made of metal foil with thin sheets of paper soaked in dielectric oil.

dry-type capacitor

similar to the wet type except a gauze us used to hold the borax solution to prevent it from leaking. if the polarity of it is reversed, the capacitor will be permanently damaged

Nonpolarized capacitors

sometimes called AC capacitors, because they are not sensitive to polarity connection

Half-wave rectification

only half of the AC waveform is converted into DC. half of the current is lost

Rochelle Salt

Its used as the needle on a record player. grooves in the record cause the crystal to twist back and forth producing an alternating voltage. This voltage is then amplified and heard as speech. Rochelle salt is also used in some microphones

momentary contact

change state when acted on, but return to their call-out state when released

inductance

henry (H), formula symbol (L), a coil has an inductance of 1 henry when a current change of 1 ampere/second results in an induced voltage of 1 volt.

couple

to join, unite

Wavelength is represented by

Lambda (λ)

copper sulfate

used in some electroplating applications, also used as a fungicide CuSO₄

volt-amperes reactive (VARS)

used to measure *reactive power* in a pure inductive circuit.

inductors in series do what to voltage and current phase?

voltage leads current by 90°

What happens when a capacitor is shorted?

when plate leads on a capacitor are shorted the atoms of the dielectric snap back to their normal position. shorting causes the electrons on the negative plate to literally be blown off and attracted to the positive plate. this is how capacitors can in some cases can produce thousands of amps in a short period of time. this principle is used to operate the flash on cameras. the flash attachments contain a small glass tube with xenon. when xenon is ionized it produces a bright light similar to sunlight.

electromagnetic induction

wherever a conductor cuts through magnetic lines of flux, a voltage is induced in the conductor. the polarity of the induced voltage is determined by the polarity of the magnetic field in relation to the direction of movement

iron core inductor

wire wound around a ferromagnetic core. cannot be used in a high frequency application due to eddy current loss and hysteresis loss in the core material.

VLSI

Very Large Scale Integration

node

junction point

wire resistance is determined by

-length -material -area -temperature

factors that determine induced voltage

-number of wire turns -strength of the magnetic field(flux density) -speed of the cutting action

factors that determine capacitance

-plate surface area -distance between the plates -type of dielectric

weber (Wb)

100,000,000 lines of flux equal 1 weber. If a conductor cuts flux at a rate of 1 weber, 1 volt is induced

capacitor

2 metal plates separated by a dielectric. Capacitors are charged by removing electrons from one plate and depositing them on another until they reach equilibrium. Once in equilibrium the battery can be disconnected and the capacitor, in theory will retain all of its charge. However, that is not the case since no dielectric is a perfect insulator. measured in Farad's (F). A capacitor has a capacitance of 1 farad when a change of 1 volt across its plates results in 1 coulomb stores energy in an electrostatic field oppose a voltage change.

inductor

A coil of wire that creates a magnetic field when current passes through it. Its function is to store energy in a magnetic field. Only works with AC since it needs changing current values to operate. If its connected to DC it will only act as a resistor. add inductors the same as adding resistors in series and parallel inductors oppose current change.

inverter

A device that converts DC to AC. You can get square wave AC by alternating switches, but if you want a sine wave you need IGBT's.

electrolysis

A process by which an electric current breaks chemical bonds. eg. aluminum oxide is an abundant compound, however aluminum by itself is not. Aluminum became inexpensive once an electrolysis process for separating it was discovered

vector

A quantity that has magnitude and direction

electromagnetic spectrum

All of the frequencies or wavelengths of electromagnetic radiation

AWG

American Wire Gauge

Faraday's Law

An electric field is induced in any region of space in which a magnetic field is changing with time.

Connecting batteries in series vs. parallel?

Connecting batteries in series gives you a higher voltage without impacting the current. Connecting batteries in parallel will raise the current but not impact the voltage.

How many lines of flux must a conductor cut through to induce 1 volt?

In order to induce 1 volt in a conductor, the conductor must cut 100,000,000 lines of magnetic flux in 1 second.

IGBT

Insulated Gate Bipolar Transistor. A three-terminal power semiconductor device primarily used as an electronic switch which, as it was developed, came to combine high efficiency and fast switching. It consists of four alternating layers (P-N-P-N) that are controlled by a metal-oxide-semiconductor (MOS) gate structure without regenerative action.

Hysteresis loss

It is also known as lagging loss. This occurs because energy is expended as the continually changing AC current magnetizes, demagnetizes, and re-magnetizes the core material. This continuous reorientation of the atoms requires energy and produces heat, thereby wasting electrical power. It only happens on AC.

What is RMS?

The RMS or root-mean-square voltage of an AC waveform is equal to the DC voltage that would produce the same amount of heat in a resistive load. For example, an incandescent light bulb would glow equally brightly when fed 120V DC or 120V RMS AC. To compute the RMS you divide up one cycle of the AC waveform into many small time slots. Square each of those voltages, take the mean of those squares, take the square root of the mean, and then you have your RMS value: the Root of the Mean of the Squares. For the common case of a simple sine wave, it's much easier. Just measure the peak voltage of the AC waveform and divide by the √2. eg. if the peak voltage is 141 volts, the RMS voltage will be 100 volts. It will light a lamp as bright as a steady stream of 100 volts of DC. RMS = peak * .707 √2 = 1.414

Kirchoff's Current Law

The current that goes into a branch is equal to the current that comes out of a branch.

single phase electricity

The distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors. A single-phase supply connected to an alternating current electric motor does not produce a revolving magnetic field; single-phase motors need additional circuits for starting (capacitor start motor), and such motors are uncommon above 10 kW in rating.

Ampacity

The maximum current a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

Kirchoff's Voltage Law

The total of all voltage drops in a series circuit must equal the voltage supplied by the battery

capacitor gunpowder analogy

Think of a capacitor as gunpowder in a bullet. If you were to remove the gunpowder from the shell and ignite it in open air, not much would happen. However, when you confine the energy within gunpowder to a small space within a bullet, the energy is released instantaneously propelling the bullet forward with great force.

3-phase electricity

Three-phase electric power is a common method of alternating current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. It is also used to power large motors and other heavy loads

induced voltage

Voltage created by the combination of movement and a magnetic field

Counter Electromotive Force (CEMF)

Voltage induced in an inductor coil which opposes the applied voltage. It is out of phase by 180 degrees.

p-n junction

a boundary or interface between two types of semiconductor materials, p-type and n-type, inside a single crystal of semiconductor. The "p" (positive) side contains an excess of holes, while the "n" (negative) side contains an excess of electrons in the outer shells of the electrically neutral atoms there. This allows electrical current to pass through the junction only in one direction. The p-n junction is created by doping.

Shunt

a device which creates a low-resistance path for electric current, to allow it to pass around another point in the circuit. In electronics, a shunt is a device which creates a low-resistance path for electric current, to allow it to pass around another point in the circuit. The origin of the term is in the verb 'to shunt' meaning to turn away or follow a different path.

alkaline cell

a primary cell that uses a zinc can as the negative electrode and manganese dioxide as the positive electrode. the major electrolyte ingredient is potassium hydroxide. it has a paste electrolyte so it can sit in any position. since it has a paste electrolyte it is considered a "dry cell"

Varistor

a resistor that changes its resistance value with a change in voltage. can be inside a surge suppressor, and capable of absorbing any excess power during a surge or spike. An electronic component with an electrical resistance that varies with the applied voltage. Also known as a voltage-dependent resistor (VDR), it has a nonlinear, non-ohmic current-voltage characteristic that is similar to that of a diode. In contrast to a diode however, it has the same characteristic for both directions of traversing current. At low voltage the varistor has a high electrical resistance which decreases as the voltage is raised. Varistors are used as control or compensation elements in circuits either to provide optimal operating conditions or to protect against excessive burst voltages. When used as protection devices, they shunt the current created by the excessive voltage away from sensitive components when triggered.

diode

a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other.

receptacle

an electrical outlet space to contain something

Anodizing

an electrolytic treating process used to increase the thickness of the natural oxide layer on the surface of metal parts.

what can cause a battery to explode?

an incorrect amount of charging current

air core inductor

an inductor that uses air or another diamagnetic material as its core

lithium ion battery

anode - lithium metallic oxide cathode - carbon

What causes power loss in an inductor?

any power used in an inductor is due to losses such as the wire resistance, eddy current loss, or hysteresis loss

When do capacitors become shorted?

capacitors become shorted when the dielectric breaks. voltage ratings for capacitors tell how much voltage stress the dielectric can withstand before it breaks.

at what rate do capacitors charge and discharge?

capacitors charge and discharge at an exponential rate. 63.2% per time constant. there are 5 time constants in one charge/discharge cycle.

wet-type capacitor

has a positive plate made of aluminum foil. the negative plate is an electrolyte made of a borax solution, a second piece of aluminum foil is placed in contact with the electrolyte and becomes the negative terminal. when a DC source is applied, the borax solution forms an insulating oxide film on the positive plate. the film is only a few molecules thick, since the distance between the plates is so small the capacitance can get very high. if the polarity is reversed, the oxide layer breaks and the capacitor is shorted. however if the polarity is corrected the oxide layer reforms.

lead acid battery

has one plate made of pure lead, a second plate made of lead dioxide, and an electrolyte dilute of sulfuric acid (H₂SO₄) overcharging a lead battery can cause hydrogen gas to be released which is the most explosive element known.

polarized capacitor

have designated terminals for positive and negative. can only be used in DC. aka electrolytic capacitor An electrolytic capacitor (e-cap) is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodization. This oxide layer acts as the dielectric of the capacitor. A solid, liquid, or gel electrolyte covers the surface of this oxide layer, serving as the (cathode) or negative plate of the capacitor. Due to their very thin dielectric oxide layer and enlarged anode surface, electrolytic capacitors have a much higher capacitance-voltage (CV) product per unit volume than ceramic capacitors or film capacitors, and so can have large capacitance values. There are three families of electrolytic capacitor: aluminum electrolytic capacitors, tantalum electrolytic capacitors, and niobium electrolytic capacitors. Electrolytic capacitors are polarized components due to their asymmetrical construction and must be operated with a higher voltage on the anode than on the cathode at all times.

What happens if the rotation speed on a generator is increased?

if the rotation speed on a generator is increased more flux lines are cut increasing the induced voltage. if more turns of wire are added more lines of flux can be cut, increasing the voltage.

no voltage low voltage drop-out protection

if there is a power outage to the device, it will require a manual restart

skin effect

in an AC circuit when electrons are forced to the outside of the conductor due to eddy currents. Forcing electrons to the outside of a conductor has the same effect as decreasing the diameter, which raises resistance. Only has a major impact when dealing with higher frequencies. To fight this, conductors with high surface area are used in high frequency applications, such as braided cable.

How is the amount of voltage produced by a cell determined?

it is determined by the materials that are used. plate metals are chosen based on how easily they will give up electrons

battery current capacity

the amount of current a particular type of cell can deliver. it is determined by the surface area of its plates

ionization potential

the amount of energy needed in order to take an electron away from an atom

inductor quality (Q)

the amount of resistance compared to inductive reactance. when Q ≥ 10 its a pure inductor

impedance (Z)

the hypotenuse of a right triangle formed by reactance and resistance

In a pure resistive circuit, current and voltage do what?

they are in phase with each other. In the pure resistive circuit, the power is dissipated by the resistors and the phase of the voltage and current remains same i.e., both the voltage and current reach their maximum value at the same time. The resistor is the passive device which neither produce nor consume electric power.

left hand generator rule

thumb = thrust forefinger = flux center finger = current