Category: Electrical Units

Electrical Units

Magnetic Units

Magnetic Units

The overall magnitude of a magnetic field is measured in units called webers, abbreviated Wb. One weber is mathematically equivalent to one volt-second (1 V . s). For weaker magnetic fields, a smaller unit,...

Magnetism

Magnetism

Electric currents and magnetic fields are closely related. Whenever an electric current flows—that is, when charge carriers move—a magnetic field accompanies the current. In a straight wire that carries electrical current, magnetic lines of...

Safety Considerations in Electrical Work

Safety Considerations in Electrical Work

For our purposes, one rule applies concerning safety around electrical apparatus: If you have any doubt about whether or not something is safe, leave it alone. Let a professional electrician work on it. Household...

Alternating Current and the Hertz

Alternating Current and the Hertz

These topics, and this whole first section, is mostly concerned with direct current (dc). That’s electric current that always flows in the same direction and that does not change in intensity (at least not...

Other Energy Units

Other Energy Units

The joule, while standard among scientists, is not the only energy unit in existence! Another unit is the erg, equivalent to one ten-millionth (0.0000001) of a joule. The erg is used in lab experiments...

Energy and the Watt-Hour

Energy and the Watt-Hour

Have you heard the terms “power” and “energy” used interchangeably, as if they mean the same thing? They don’t! Energy is power dissipated over a length of time. Power is the rate at which...

A Word about Notation

A Word about Notation

Have you noticed some strange things about the notation yet? If you’re observant, you have! Why, you might ask, are italics sometimes used, and sometimes not used? Something should be said early in this...

Power and the Watt

Power and the Watt

Whenever current flows through a resistance, heat results. The heat can be measured in watts (symbolized W) and represents electrical power. (As a variable quantity in equations, power is denoted by the uppercase italic...

Conductance and the Siemens

Conductance and the Siemens

Electricians and electrical engineers sometimes talk about the conductance of a material, rather than about its resistance. The standard unit of conductance is the siemens, abbreviated S. When a component has a conductance of...

Resistance and the Ohm

Resistance and the Ohm

Resistance is a measure of the opposition that a circuit offers to the flow of electric current. You can compare it to the diameter of a hose. In fact, for metal wire, this is...

The Ampere

The Ampere

Current is a measure of the rate at which charge carriers flow. The standard unit is the ampere. This represents one coulomb (6,240,000,000,000,000,000) of charge carriers flowing every second past a given point. An...

Current Flow

Current Flow

If a conducting or semiconducting path is provided between two poles having a potential difference, charge carriers flow in an attempt to equalize the charge between the poles. This flow of current continues as...

The Volt

The Volt

An accumulation of electrostatic charge, such as an excess or shortage of electrons, is always associated with a voltage. There are other situations in which voltages exist. Voltage can be generated at a power...