What is Resistor

Chapter Resistors

Teach Yourself Electricity and Electronics Third Edition Book
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Summary of Contents

Teach Yourself Electricity and Electronics Third Edition Book

  • Electrical insulators can be forced to carry current. Ionization can take place; whenelectrons are stripped away from their atoms, they have no choice but to move along.Sometimes an insulating material gets charred, or melts down, or gets perforated by aspark. Then its insulating properties are lost, and some electrons flow.An insulating material is sometimes called a dielectric. This term arises from thefact that it keeps electrical charges apart, preventing the flow of electrons that wouldequalize a charge difference between two places. Excellent insulating materials can beused to advantage in certain electrical components such as capacitors, where it is im-portant that electrons not flow.Porcelain or glass can be used in electrical systems to keep short circuits from oc-curring. These devices, called insulators, come in various shapes and sizes for differentapplications. You can see them on high-voltage utility poles and towers. They hold thewire up without running the risk of a short circuit with the tower or a slow dischargethrough a wet wooden pole.ResistorsSome substances, such as carbon, conduct electricity fairly well but not really well. Theconductivity can be changed by adding impurities like clay to a carbon paste, or by wind-ing a thin wire into a coil. Electrical components made in this way are called resistors. Theyare important in electronic circuits because they allow for the control of current flow.Resistors can be manufactured to have exact characteristics. Imagine telling eachperson in the line that they must pass a certain number of balls per minute. This is anal-ogous to creating a resistor with a certain value of electrical resistance.The better a resistor conducts, the lower its resistance; the worse it conducts, thehigher the resistance.Resistors131-5In a conductor, electrons are passed from atom to atom.