Electrical Systems

For the ASVAB

Direct Current (DC)

Moves in one direction only, often used in batteries, through it can also be generated by using rectifiers.

Alternating Current (AC)

A type of electrical flows that constantly changes its direction at regular intervals, commonly produced by alternators and is standardized in household appliances.

Alternator

This device generates continuously changing flows by rotating a wire within a magnetic field the changing position of the wire relative to the field causes the flow direction to reverse repeatedly.

Impedance

The overall opposition to charge flow in an alternating system, acts analogously to resistance, capacitors and inductors are counted for.

Frequency

= how many complete cycles an alternating waveform completes in one second, the standard deviation is 60 hertz

Hertz

Unit of measurement for waveform cycles per second, ranging from zero to gigahertz

Frequencey Formula

Determines the rate of waveform cycles by inverting the time period of one cycle, Formula:(f=1/T)

Grounding

Neutralizes a charged object by connecting it to a massive charge reservoir like the earth, prevents electric shock during faults.

Resistor

Reduces charge flow and potential differences levels within a system, often marked with colored bands that indicate value & tolerance

Fixed Resistor

Provides a single unchanging value of opposition to charge flow, common types include carbon composition, wire wound, and metal film

Variable Resistor

Allows opposition value to manually adjusted within a range, it’s often used in devises requiring frequent tuning like a TV volume dial

Potentiometer

Features terminals at each end and a movable central contact, it’s commonly utilized in electronics as a voltage divider

Rheostat

Two-terminal that functions as a current-limiting device, it typically has a power rating over two watts and is used to control lighting levels

Fuse

Protects systems form power overloads by physically breaking the pathway, disrupts the flow before unwanted power surges

Short Circuit

Occurs when electrical flow takes an unintended pathway that is faster than designed resulting in a massive surge of charges

Capacitor

Stores electrical energy using two conducting plates separated by a dielectric, it can discharge stored energy to a system (ex: battery)

Capacitance Formula

= the energy storage ability of a component based on charge and potential difference, Formula: (C= Q/V)

Farad

A unit used to measure the energy storage capacity to two polarized how much charge is stored per unit of potential difference

Capacitive Reactance

Describes the opposition an energy-storing component provides in response to an alternating frequency, Formula: _Xc= 1/ w*C

Doping

Alters a semiconducting material’s properties by adding impurities, it makes the material either more or less conductive using electrons

Diode

Restricts charge flow a single direction and block the reverse, it’s formed by joining P-type & N-type materials to create a junction

Forward-Biased

Occurs when voltage source’s polarity allows charges to flow freely through a junction, requiring the positive terminal to connect to the anode

Reverse-Biased

Happens when a voltage source’s polarity prevents charges from passing through a junction, it blocks the flows pathway

Rectification

Coverts an alternating signal into a unidirectional flow, it’s utilized in power supplies to create a usable output from wall lines

Transistor

Three-terminal solid-state component is used to regulate, amplify, or switch electrical signals, constructed from altering layers of semiconductors

NPN Transistor

Solid-state arrangements sandwiches a thin layer of P-type material between two N-type layers, acts as an amplifier or switch in electronic logic

PNP Transistor

Solid-state arrangements sandwiches a thin layer of N-type material between two P-type layers, controls charge movement differently

Magnetic Field

Movement of charged particles, either atomically or macroscopically. It can be created artificially

Inductor

Opposes sudden changes in charge flow by generating a counter-electromotive force, it consists of a conductive wire coiled around a core

Transformer

Coverts voltages form high to low or vice versa, using two nearby coiled components, the differing coils induces the voltage change