potential and capacitance

Conservation of Mechanical Energy

Conservation of Mechanical Energy In this section, we examine what happens to this mechanical energy when only conservative forces cause energy transfers within the system-that is, when frictional and  forces do not act on the objects in the system. In an isolated system where only conservative forces cause energy changes, the kinetic energy and potential energy …

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Practical capacitors

Practical capacitors Capacitors playa very important part today in various electrical circuits, especially radio circuits. For practical purposes, capacitance is measured in microfarads (IlF). A microfarad is a millionth part of a farad (page 388). Three common types of capacitor are illustrated in Fig. 33.12. Fig. 33.12 (a) shows a variable capacitor of the kind used for tuning radio …

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The leyden jar

The leyden jar We are now in a position to understand why Musschenbroek received so severe a shock from the Leyden jar described on page 389. His hand, holding the outside of the bottle, acted as an earthed conductor separated by a glass dielectric from the conducting water inside. The arrangement thus formed a capacitor. Later on, the …

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Factors affecting the capacitance of a parallel-plate capacitor

Factors affecting the capacitance of a parallel-plate capacitor The three factors which affect the capacitance of a parallel-plate capacitor are the area of the plates, the distance apart of the plates and the nature of the insulating material or dielectric between them. These factors may be investigated by the following experiments. (1) Area of plates The effect of …

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Capacitance in electric machines

Capacitance in electric machines During the eighteenth century a large variety of electric machines were constructed, mostly consisting of glass globes or plates which were rotated against rubbing pads or even the human hand. These machines were capable of producing a succession of small sparks, but later it was discovered that much fatter sparks could be obtained …

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Capacitance

Capacitance If equal quantities of water are poured into vessels of different diameters the water will come up to different levels in each. Similarly, when equal charges are given to conductors of different sizes they will acquire different potentials. This may be demonstrated by standing two unequal metal cans on the caps of two identical electroscopes (Fig. 33.5 …

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Potential over the surface of a charged conductor

Potential over the surface of a charged conductor Where static electricity is concerned, the potential is the same an over a charged conductor, no matter how the charge or charges may be distributed over it. Thus, in the experiment illustrated in Fig. 33.3 (a) the negatively charged rod produces a potential difference between the ends of the insulated …

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Potential and the gold-leaf electroscope

Potential and the gold-leaf electroscope In the previous chapter we looked upon a gold-leaf electroscope as an instrument chiefly for the purpose of indicating the presence or sign of an electric charge, or for making ‘a rough measurement of quantity of charge. Actually, the leaf divergence of a gold-leaf electroscope indicates that there is a potential difference …

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