Electrical Terms

Understanding electrical terms is compulsory for engineers. As you study electricity in your engineering program, and as you work with electricity in power plants, and industrial plants, you will hear, read, and use various electrical terms. These terms have very exact meanings. You must know what each one means if you are to understand other people and make them understand you. The following terms explain the meaning of the most basic electrical terms.

Electric current the electrical term:

Electric current is one of the basic electrical terms described as when electrons flow from one place to another, they make a current. The electrons always flow from a negative point to a positive (or less negative) point, because electrons have a negative charge.

Unfortunately, the direction of the current flow can be confusing. Some people think of a positive current that is in the opposite direction from the electron flow- that is, from positive to negative instead of from negative to positive. You must be careful to distinguish between the two kinds of flow. Both kinds are commonly used in words and diagrams.

The so-called “positive current” is from positive to negative. The “electron flow” is from negative to positive. The word “current” means electron flow from negative to positive. The figure below shows the difference between positive current and electron flow.

Circuit:

Electrons flow along with some kind of path going from one point to another. This path is called a circuit. If the path has no gaps to stop the flow of electrons, the circuit is said to be complete or closed.

In case the path has a gap that the electrons cannot cross- for example, a break in a wire where the ends are separated by air- the circuit is said to be open. If another pathway provides an easier way a short circuit for the electrons to go from one point to another, that part of the circuit is said to be shorted. The figure below shows the circuit that is complete, open, and short.

Potential difference:

This term is the correct name for what is often called “voltage” or “electromotive force.” Potential difference is a measure of how much potential energy an electron has in one place compared to another place.

The greater the potential energy, the more work an electron can do in going from one place to the other. The potential energy of each electron also determines how much current will flow from one point to another in a given circuit.

Resistance:

Every electrical pathway from one place to another has the property of resisting the flow of electrons. Some pathways resist the flow only slightly. For example, a thick copper wire offers very little resistance. Other pathways- for example, an air gap-offer great resistance. The greater the resistance, the less the current for a given potential difference.

Cell:

Electricity can be produced by chemical means. The arrangement of materials that produces a potential difference between two points by chemical resources is called a cell. Familiar cells include the dry cells used in flashlights, calculators, and radios.

Battery:

When you connect two or more cells together, the combination is called a battery. If your calculator takes two dry cells, the grouping is called a two-cell battery.

The storage battery in a car or truck is usually a six-cell battery that produces a potential difference of 12V between the terminals. Each cell in such a battery produces a potential difference of 2 V between its internal terminals. The terminals of the cells are connected in such a way that their potential differences add together between the external terminals

As you study the remaining lessons in this course and the other courses in your series, make sure you learn the proper terms to use in discussing electricity, and the exact meaning of each term. Always use the correct terms, even if other people do not. If you use the wrong terms, you are likely to be misunderstood. In addition, other people will think you know less about electricity than you actually do.

Conductor:

A material that allows the easy flow of electric current due to its high conductivity. Common conductors include metals like copper and aluminum.

Insulator:

A material that restricts the flow of electric current due to its low conductivity. Insulators are used to prevent electrical leakage and include materials like rubber and plastic.

Voltage (Voltage Drop):

Voltage, measured in volts (V), is the electrical potential difference between two points in a circuit. It represents the force that pushes electrons through a conductor. Voltage drop refers to the decrease in voltage along a conductor due to its resistance.

Current (Amperage):

Current, measured in amperes (A), is the rate of flow of electric charge (electrons) in a circuit. It indicates how many electrons pass through a point in a circuit per unit of time.

Ohm’s Law:

A fundamental relationship in electricity that states the current (I) flowing through a conductor is directly proportional to the voltage (V) across it and inversely proportional to the resistance (R) of the conductor. It is expressed as V = I * R.

Resistor:

A passive component in a circuit is designed to introduce a specific amount of resistance to control the flow of current. Resistors are commonly used for voltage division and current limiting.

Power:

Power, measured in watts (W), is the rate at which electrical energy is consumed or produced in a circuit. It can be calculated using the formula P = V * I, where V is voltage and I is current.

Circuit Breaker:

A safety device used in electrical circuits to protect against overcurrent and prevent electrical fires. It opens (breaks) the circuit when excessive current flows, thus interrupting the power supply.

Fuse:

A safety device that contains a thin wire that melts when excessive current flows through it, breaking the circuit and protecting against overcurrent. Fuses need to be replaced after they “blow.”

Ground:

The reference point in an electrical circuit is typically connected to the Earth for safety reasons. Grounding helps protect against electrical shock and ensures stable operation of equipment.

AC (Alternating Current):

AC is an electrical current that periodically reverses direction, causing the voltage to alternate between positive and negative values. Most household electricity is AC.

DC (Direct Current):

DC is an electrical current that flows consistently in one direction, with a constant polarity. Batteries and many electronic devices use DC power.

Transformer:

A device that changes the voltage level of AC electricity. Transformers are used for voltage step-up (increasing voltage) or voltage step-down (decreasing voltage) and are crucial in power distribution.

Capacitor:

An electronic component that stores electrical energy in the form of an electric field. Capacitors are used in circuits for various purposes, including energy storage and timing.

Inductor:

An electronic component that stores electrical energy in the form of a magnetic field when current flows through it. Inductors are used in circuits for filtering and energy storage.