The Definition of Energy

Before going much further you should first learn the fundamental definition of energy. For example, is light by itself energy? Is electrical energy measured in watts, or in calories for heat? Up until now you may have thought so, but let's get a strict definition of energy to start off with and then proceed with how to measure it.

Simply put, energy is the capacity to do work.

Very good! Now what do we mean by work? Is it a job you go to after school or on the weekend? Not hardly, at least not for a strict definition of energy.

Work is done when a force moves an object.

Two things need to be measured:

1. The amount of the force used to move the object

2. The distance that the object moves.

Multiplying these two quantities together (Force x Distance) gives the numerical size of the work done. And combining the units used to measure the force and the distance defines the units for work.

The common symbol for energy is the uppercase letter E and the standard energy unit is the joule, symbolized by J. Joules can be defined in terms of both mechanical energy familiar from the above definition of work, and electrical energy in circuits, which is a measure of power expended over time

The standard energy unit: the joule (J)

/-""n. Mechanical Energy: One joule (1 J) is the energy resulting from the equivalent of one 1 newton (1 N) of force acting over one meter (1 m) of displacement.

Electrical Energy: One joule (1 J) is equivalent to one watt (1 W) dissipated or radiated for one second (1 s).

A common unit of energy in electric utilities is the kilowatt-hour (kWh), which is the equivalent of one kilowatt (kW) dissipated or expended for one hour (1 h). Because

1 kW = 1000 W and 1 h = 3600 s, 1 kWh = 3.6 x 106 J.

We will be using other units of measure, including volts, amps, ohms, watts and hertz, as we conduct the experiments in the upcoming chapters.

Electrons are one of the three fundamental parts of an atom, along with protons and neutrons. One or more protons and neutrons stick together in the center of the atom to form the nucleus. The tiny electrons orbit around the nucleus. Electrons repel each other, and electrons and protons attract each other.

Charge: The tendency for an electron to repel from another electron and attract to a nearby proton is called negative charge. The tendency for a proton to repel from another proton and attract an electron is called positive charge. Negatively charged molecules have more electrons that protons; positively charged molecules have fewer electrons than protons. A molecule with an equal number of electrons and protons is neutrally charged.

The volt (V) is the unit of measurement for electrical pressure. Voltage can be thought of as electrical pressure caused by the attraction of electrons in a negatively charged molecule to the protons of a positively charged molecule.

The ampere, or amp, (A) is the unit of measurement for current. Current with refers to the number of electrons per second passing through a circuit. Current is commonly denoted by the letter "I" in schematics and equations.

The ohm (O) is the basic unit of measurement for resistance. Resistance (R) is the ability of an element in a circuit to inhibit the flow of current.

Ohm's Law: The relationship among voltage, current, and resistance is defined as which states: "The voltage measured across a resistor's terminals (V) equals the current passing thought the resistor (I) times the resistor's resistance (R). "

DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

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