Automotive Electricity and Electronics - Comprehensive Vocabulary

Comprehensive practice vocabulary flashcards covering basic electrical theories, components, circuits, starting and charging systems, vehicle networks, lighting, and safety systems from Today's Technician: Automotive Electricity and Electronics, 7th Edition.

Ohm's Law

The fundamental electrical law defining the mathematical relationship between voltage, current, and resistance: $E = I \times R$ (or $V = I \times R$). It states that it takes one volt of electrical pressure to push one ampere of current through one ohm of resistance.

Watt's Law

The mathematical formula expressing the relationship between electrical power, voltage, and current: $P = E \times I$, where power ($P$) is measured in watts.

Kirchhoff's Voltage Law

The electrical principle stating that the algebraic sum of all voltage sources and voltage drops around any closed electrical circuit loop must equal zero.

Kirchhoff's Current Law

The electrical principle stating that the algebraic sum of all currents entering and leaving any junction or point in an electrical circuit must equal zero.

Electromotive Force (EMF)

The electrical pressure or potential difference, measured in volts, that forces electrons to move through a conductor.

Conductor

A material, typically having three or fewer electrons in its valence ring (such as copper), that readily permits the flow of electrical current.

Insulator

A material whose atoms possess five to eight electrons in their outer valence ring, binding them tightly to the nucleus and preventing the easy flow of electrons.

Semiconductor

A material possessing four electrons in its outer valence ring (such as silicon or germanium) that acts neither as a good conductor nor as a good insulator, but conducts electricity under controlled conditions.

Voltage Drop

The loss of electrical pressure (voltage) that occurs when current flows through a resistance or load, representing the conversion of electrical energy into another energy form, such as heat or light.

Electromagnetic Induction

The production of voltage across a conductor when relative motion occurs between the conductor and magnetic lines of force.

Counter Electromotive Force (CEMF)

An induced voltage generated within a motor's spinning armature windings that opposes the source voltage, naturally reducing current draw as motor speed increases.

Specific Gravity

The weight of a given volume of liquid divided by the weight of an equal volume of pure water; a fully charged lead-acid battery has a specific gravity of $1.265$ corrected to $80^\circ\text{F}$ ($26.7^\circ\text{C}$).

Absorbed Glass Mat (AGM) Battery

A sealed lead-acid battery design that immobilizes the liquid electrolyte within porous, fine fiberglass mat separators compressed between high-purity lead plates.

Valve-Regulated Lead-Acid (VRLA) Battery

A sealed, recombinant battery design that immobilizes electrolyte and uses one-way pressure-relief valves, recombining internally generated oxygen and hydrogen back into water.

Armature

The movable, rotating component of an electric motor or generator consisting of copper conductor coils wound around a laminated iron core mounted on a steel shaft.

Commutator

A ring of insulated copper segments mounted at one end of an armature that periodically reverses current direction through the armature coils via stationary sliding brushes.

Overrunning Clutch

A roller-type mechanical clutch mechanism in a starter drive that transmits driving torque from the starter motor to the engine flywheel ring gear, but freewheels when the engine runs faster than the starter.

Stator

The stationary, circular laminated iron core and three-phase wire winding assembly of an AC generator or motor in which alternating current is induced or a rotating magnetic field is generated.

Rotor

The rotating electromagnet assembly of an AC generator, consisting of a field coil wrapped on an iron core and enclosed between interlocking north and south pole pieces, driven by a drive belt.

Rectification

The process of converting alternating current ($\text{AC}$) into direct current ($\text{DC}$), accomplished in an alternator by a diode rectifier bridge.

Diode Trio

A dedicated group of three diodes inside an alternator used to rectify three-phase AC stator output into DC current to supply the rotor's field windings.

High-Side Driver (HSD)

A solid-state transistor driver located inside an electronic control module that switches and controls the positive power feed side ($12\,\text{V}$) to an actuator or load.

Low-Side Driver

A transistor driver circuit inside a control module that operates an electrical load or actuator by completing its circuit path to ground.

Controller Area Network (CAN)

A high-speed, differential two-wire serial data bus protocol (utilizing CAN High and CAN Low twisted wires) that provides reliable real-time communication between multiple electronic control modules.

Local Interconnect Network (LIN)

A low-cost, single-wire sub-network protocol that uses a single master node to control and poll multiple smart sensors and slave actuator modules at speeds up to $20\,\text{kb/s}$.

Media-Oriented System Transport (MOST)

A high-speed optical data network bus that utilizes plastic fiber-optic cables in a ring topology to transmit automotive digital audio and video data at speeds up to $25\,\text{Mb/s}$.

Hall-Effect Sensor

A solid-state sensor that generates a small transverse voltage signal when an internal semiconductor layer carrying current is exposed to an external perpendicular magnetic field.

Piezoresistive Device

A pressure or strain sensor whose internal electrical resistance changes in direct response to mechanical stress or physical deformation.

Piezoelectric Sensor

A sensor that directly generates an electrical voltage output when subjected to mechanical compression, vibration, or physical shock.

Potentiometer

A three-terminal variable resistor configured as a voltage divider, utilizing a movable wiper across a fixed resistive element to output a variable DC voltage proportional to mechanical position.

Rheostat

A two-terminal variable resistor wired in series with an electrical load to manually regulate the intensity of current flow.

Thermistor

A solid-state variable resistor constructed of semiconductor metal oxides whose electrical resistance changes predictably with temperature.

Negative Temperature Coefficient (NTC) Thermistor

A thermistor whose electrical resistance decreases as operating temperature increases.

Positive Temperature Coefficient (PTC) Thermistor

A thermistor whose electrical resistance increases as operating temperature increases, commonly utilized as a self-resetting solid-state circuit protection device.

Wheatstone Bridge

A circuit arrangement of four resistors in two parallel branches across a voltage source, designed to detect minute changes in resistance by measuring differential voltage across the center bridge.

Clockspring

A continuous conductive flat ribbon cable wound within a plastic case on the steering column, maintaining unbroken electrical connections to the driver air bag, horn, and steering wheel switches as the wheel turns.

Occupant Restraint Controller (ORC)

The dedicated microprocessor module that monitors supplemental restraint system (SRS) crash sensors, stores backup reserve power, and fires air bag squibs and seat belt pretensioners during an impact.

Squib

A small pyrotechnic igniter element containing a fine wire and an explosive charge (such as zirconic potassium percolate) that initiates the chemical propellant reaction in an air bag inflator.

Seat Belt Pretensioner

A pyrotechnic device integrated into the buckle or retractor that rapidly reels in seat belt slack within milliseconds of a collision to firmly hold the occupant in place.

Integrated Starter Generator (ISG)

An electronically controlled AC electric machine mounted on the engine crankshaft or driven by a belt that combines the functions of the starter motor, high-output generator, idle stop/start actuator, and regenerative braking device.

Regenerative Braking

A process during vehicle deceleration that converts vehicle kinetic energy into electrical energy by utilizing drive motors as generators to recharge the high-voltage battery or capacitors.

Proton Exchange Membrane (PEM)

A specially treated polymer electrolyte foil in a fuel cell that allows only positive hydrogen protons ($\text{H}^+$) to pass from the anode to the cathode, forcing electrons through an external circuit to do electrical work.

High-Intensity Discharge (HID) Lamp

An automotive headlight that produces high-luminance light by sustaining an electric arc across two tungsten electrodes inside a quartz capsule filled with xenon gas, mercury, and metal halide salts.

Bi-Xenon Headlamp

A headlight assembly that uses a single high-intensity discharge (HID) xenon arc bulb to produce both low-beam and high-beam light patterns, modulated by an electro-mechanical shutter.

Fusible Link

A short length of wire constructed with meltable conductor material and fire-resistant insulation, typically four gauge sizes smaller than the circuit wire it protects, that opens during an extreme overload.

Relay

An electro-mechanical switch containing an electromagnetic coil that uses a small amount of control current to open or close contacts capable of carrying high current to a load.

Solenoid

An electromagnetic actuator consisting of an electrical coil and a movable iron plunger that performs mechanical movement and/or high-current electrical switching when energized.

Peltier Element

A solid-state thermoelectric device made of joined dissimilar semiconductor metals that absorbs or generates thermal energy when direct current is applied, utilized in climate-controlled seats.