Magnetism is a result of electrons spinning on their own axis around the nucleus (Figure 18). In magnetic materials, the atoms have certain areas called domains. These domains are aligned such that their electrons tend to spin in the same direction (Figure 19). The alignment of these domains results in the formation of magnetic poles [...]
Thermionic Emission A thermionic energy converter is a device consisting of two electrodes placed near one another in a vacuum. One electrode is normally called the cathode, or emitter, and the other is called the anode, or plate. Ordinarily, electrons in the cathode are prevented from escaping from the surface by a potential-energy barrier. When [...]
Photoelectric Effect Light is a form of energy and is considered by many scientists to consist of small particles of energy called photons. When the photons in a light beam strike the surface of a material, they release their energy and transfer it to the atomic electrons of the material. This energy transfer may dislodge [...]
Thermoelectricity Some materials readily give up their electrons and others readily accept electrons. For example, when two dissimilar metals like copper and zinc are joined together, a transfer of electrons can take place. Electrons will leave the copper atoms and enter the zinc atoms. The zinc gets a surplus of electrons and becomes negatively charged. [...]
Piezoelectric Effect By applying pressure to certain crystals (such as quartz or Rochelle salts) or certain ceramics (like barium titanate), electrons can be driven out of orbit in the direction of the force. Electrons leave one side of the material and accumulate on the other side, building up positive and negative charges on opposite sides, [...]
Static Electricity Atoms with the proper number of electrons in orbit around them are in a neutral state, or have a “zero charge.” A body of matter consisting of these atoms will neither attract nor repel other matter that is in its vicinity. If electrons are removed from the atoms in this body of matter, [...]
Electrochemistry Chemicals can be combined with certain metals to cause a chemical reaction that will transfer electrons to produce electrical energy. This process works on the electrochemistry principle. One example of this principle is the voltaic chemical cell, shown in Figure 11. A chemical reaction produces and maintains opposite charges on two dissimilar metals that [...]
System Internationale (SI) Metric System Electrical units of measurement are based on the International (metric) System, also known as the SI System. Units of electrical measurement include the following: Ampere Volt Ohm Siemens Watt Henry Farad Appendix A provides more information concerning the metric system, metric prefixes, and powers of 10 that are used in [...]
Conductors Conductors are materials with electrons that are loosely bound to their atoms, or materials that permit free motion of a large number of electrons. Atoms with only one valence electron, such as copper, silver, and gold, are examples of good conductors. Most metals are good conductors. Insulators Insulators, or nonconductors, are materials with electrons [...]
Free Electrons Electrons are in rapid motion around the nucleus. While the electrostatic force is trying to pull the nucleus and the electron together, the electron is in motion and trying to pull away. These two effects balance, keeping the electron in orbit. The electrons in an atom exist in different energy levels. The energy [...]
[Online Article is proudly powered by WordPress.]