DC THEORY

AC power supply

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Capacitor

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DC Power supply

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Inductor Iron Core

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Neutron

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Proton

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Relay

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Transformer

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GIVEN: E= 1.5 Volts R=5 ohms I=?

.3 amps

Given: E=3 Volts R= 5 ohms I=?

.6 amps

Given: E= 24 Volts R= 2.4 ohms P=?

240 watts

Given: I= 10 amps E= 24 Volts P=?

240 watts

Given: R= 2.4 ohms I= 10 amps P=?

240 watts

GIVEN: R1 = 10 ohms R2 = 15 ohms R3 = 30 ohms Find the Total resistance?

55 ohms

Battery

A device for converting chemical energy into electrical energy.

Load

A device through which an electric current flows and one that changes electrical energy into another form; power consumed by a device or circuit in performing its function.

Switch

A device to connect, disconnect, or change the connections in an electrical circuit.

Fuse

A device used to protect a circuit from an excessive amount of current flow in the circuit.

Schematic Circuit Diagram

A diagram using symbols to indicate devices in a circuit. Schematics show function, not location.

Ferromagnetic Material

A highly magnetic material, such as iron.

Short Circuit

A low resistance connection between two points of different potential in a circuit, usually accidental and usually resulting in excessive current flow that may cause damage.

Insulator

A material used to prevent the leakage of electricity from a conductor and to provide mechanical spacing or support to protect against accidental contact; a material in which current flow is negligible, used to surround or separate a conductor to prevent loss of current.

Conductor

A material with a large number of free electrons; a material that permits electric current to flow.

Cell

A single unit that transforms chemical energy into electrical energy. Batteries are made up of cells.

Wire

A solid or stranded group of solid, cylindrical conductors having low resistance to current flow, with any associated insulation.

Element

A substance in chemistry that cannot be divided into simpler substances by any means normally available.

Semiconductor

A substance that can conduct electricity under some conditions.

Coulomb's Law

Also called the law of electric charges or the law of electrostatic attraction. Coulomb's law states that charged bodies attract or repel each other with a force that is directly proportional to the product of their individual charges and inversely proportional to the square of the distance between them.

Direct Current (DC)

An electric current that flows in one direction.

Ion

An electrically charged atom or group of atoms. Negative ions have an excess of electrons; positive ions have a deficiency of electrons.

Coil

An inductive device created by looping turns of wire around a core.

Ammeter

An instrument for measuring the amount of electron flow in amperes.

Matter

Any physical entity that possesses mass.

Electrical Charge

Electrical energy stored on or in an object. The negative charge is caused by an excess of electrons; the positive charge is caused by a deficiency of electrons.

Insulators

High resistance to transfer of electrons.

True

If a magnet attracts material this indicates the material must itself be a magnet at the time of attraction.

Law of Magnetic Poles

Like poles repel; unlike poles attract.

Electrostatic

Pertaining to electricity at rest, such as charges on an object

Any time there is a significant difference of electrical charge between two components or objects they have..

Potential Difference

Power Rating

Rate at which a device converts electrical energy into a more useful form.

Magnetic Field

Region in which magnetic forces created by a permanent magnet or by a current-carrying conductor or coil can be detected.

Voltage

Signifies electrical pressure, is a force that causes current to flow through an electrical conductor.

Static Electricity

Stationary electricity that is in the form of a charge. It is the accumulated charge of an object.

Energy

The ability or capacity to do work.

Induction

The act or process of producing voltage by the relative motion of a magnetic field across a conductor.

Ampere

The basic unit of measure for an electrical current.

Circuit

The complete path of an electric current.

Ohm's Law

The current in an electrical circuit is directly proportional to the electromotive force in the circuit. The most common form of the law is E = IR, where E is the electromotive force or voltage across the circuit, I is the current flowing in the circuit, and R is the resistance in the circuit.

Source

The device that furnishes the electrical energy used by a load.

Voltage Drop

The difference in voltage between two points. It is the result of the loss of electrical pressure as current flows through a resistance.

Current (I)

The drift of electrons past a reference point; the passage of electrons through a conductor. It is measured in amperes.

Resistor

The electrical component that offers resistance to current flow. It may be a coil of fine wire or a composition rod.

Electron

The elementary negative charge that revolves around the nucleus of an atom.

Voltage is Increased...

The flow is increased.

Electromotive Force (EMF)

The force that causes electricity to flow between two points with different electrical charges; or when there is a difference in potential between the two points, the unit of measure in volts.

Resistance (R)

The opposition of current flow through a conductor, measured in ohms. All conductors possess some resistance, but when a device is made especially for the purpose of limiting current flow, it is called a resistor.

Watt

The practical unit of electrical power. It is the amount of power used when 1 ampere of direct current flows through a resistance of 1 ohm.

Power (P)

The rate of doing work or the rate of expending energy. The unit of electrical power is the watt.

Ohm

The unit of electrical resistance. It is the value of electrical resistance through which a constant potential difference of 1 volt across the resistance will maintain current flow of 1 ampere through the resistance. Ohm is identified by the Greek letter Ω.

Voltmeter

This instrument is a device for measuring voltage.

Conductors

Transfer electrons very easily.

Magnetism

generally defined as that property of material that enables it to attract pieces of iron.

Voltage is Decreased...

the flow is decreased