Direct Current (DC) Basic Terms (LEVEL A)

Battery

- A device consisting of a number of primarily voltaic cells (cells that cannot be recharged) or secondary cells (cells that can be recharged) connected in series to obtain a desired DC voltage - A battery stores chemical energy and makes the energy available in the electrical form - Aircraft storage batteries are generally rated at 12 or 24 volts

Magnetism

- Ability of a magnet to attract certain material containing iron and to influence electrons - Magnetism is the principal way to effectively produce AC electricity

Farad

- Basic unit of capacity - One farad holds one coulomb under a pressure of one volt

Volt (V)

- Basic unit of electrical pressure - A volt is the amount of force required to cause one amp of current to flow through one ohm or resistance - Volt is often expressed by such terms as voltage, voltage drop, potential difference, EMF, or IR drop

Coulomb

- Basic unit of electrical quantity - A coulomb is equal to 6.28 billion - billion electrons (6.28 X 10 to the 18th)

Henry (H)

- Basic unit of measurement for inductance of an electrical coil - One henry is the inductance of a coil when a charge of current of one ampere per second induces an e.m.f. of one volt - In mathematical problems inductance is expressed by the symbol "L"

Watts (W)

- Basic unit of power that is the product of voltage multiplied by current - One watt is the power produced in a circuit that has one amp of current flowing under a pressure of one volt

Inductor

- Coil or other device used to introduce into a circuit - An inductor is winding, or coiling, of multiple turns of wire

Conductor

- Common building block of electrical circuits that easily permits the movement of electrons from an electrical source to a load and back to the electrical source with a minimum of resistance - A conductor's resistance depends on such factors as cross sectional area, length, temperature, and conductor material

Electron

Negatively charged subatomic particles that are located and travel around (orbit) the nucleus in an imaginary sphere or shell at the speed of light (186,000 miles/second) - Electrons are involved in the conduction of electricity

Resistance (R)

- Electrical characteristic of a conductor - Opposition that a circuit, component, or substance presents to the flow of electricity - Resistance is the force that opposes or slows down another face, drops voltage, and consumes power - Resistance is measured in ohms - In mathematical problems ohms of resistance is expressed by the symbol "R"

Static Electricity

- Electrical charge that may be build up on a non-conductive surface by friction - Static electricity serves no useful purpose

Capacitor

- Electrical component used to store electrical energy in the form of an electrostatic field - A capacitor is a device made of two parallel conductors separated by an insulator

Direct Current

- Flow of electron in one direction through a circuit with constant voltage and current - Direct current is caused by a constant difference of potential, both negative and positive

Insulator

- Material or device used to prevent the passage of heat, electricity, or sound from one medium to another

Working Voltage

- Maximum amount of DC voltage that can be safely applied across a capacitor

Magnetic Permeability

- Measure the ease that lines of flux travel through a material

Metric Prefixes

- Measurements relating or using the metric the metric system of measurement

Neutron

- Neutral subatomic particles that exist within the nucleus of all atoms - Neutrons are not involved in the conduction of electricity

Ohm's Law

- Ohm's law states that "the amount of current flowing in a circuit is directly proportional to the circuit voltage and inversely proportional to the circuit resistance" - A plain language statement for Ohm's Law is; One volt causes one ampere to flow through a resistance of one ohm.

Proton

- Positively charged subatomic particles that exist within the nucleus of all atoms - Protons are not involved in the conduction of electricity

Left-Hand Rule

- Refers to electrical generators - This rule is for determining the direction of movement of a current-carrying conductor in a magnetic field

Scientific Notation

- Short way of expressing a given number as a number between 1 and 10 and multiplied by 10 to the appropriate power

Current

- The flow of electrons through a conductor is known as current flow - The rate of current flow is measured in amperes

E.M.F.

- The force that causes electrons to flow through a conductor - The unit of measurement for electromotive force is the volt - In mathematical problems voltage is expressed by the letter "E"

Ohm

- Unit of electrical opposition to the flow of current - A circuit has one ohm of resistance when it limits the flow of current to one amp under a voltage pressure of one volt

Ampere

- Unit of measurement used to express the flow of electrons (electrical current) - One ampere is a rate of flow of one coulomb (6.28 billion - billion electrons) passing a given point in an electrical circuit per second - In mathematical problems amperage is expressed by the letter "I"