Langsung ke konten utama

Resistance


Figure 1
    It may be defined as the property of a substance due to which it opposes the flow of electricity (Read: The Ide of Electric Potential) throug it. 
     Metal (as a class), acids and salt solutions are good conductors of electricity. amongst pure metals, silver, copper, and aluminium are vey good conductors in the given order. This, as discussed earlier (Read: Modern Electron Theory), is due to the presence of a large number of free or loosely-attached electrons in their atoms. These vagrant electrons assume a derected motion on the application of an electric potential difference. These electrons while flowing pass throug the molecules or the atoms of the conductor, collide with other atoms and electrons, thereby producing heat.
               Figure 2 metal ( https://www.imperiummultiniaga.com)

   Figure 3 copper (http://www.hoo-tronik.com)
    These substances which offer relatively greater difficulty or hindrance to the passage of these electrons are said to be relatively poor conductors of electricity like bakelite, mica, glass, rubber, p.v.v (polyvinly chloride ) and dry wood etc. amongst good insulators can be included fibrous substance such as paper and cotton when dry, mineral oils free from acids and water, ceramics like hard porcelin and asbestos and many other plastics besides p.v.c. 
Label:

Komentar

Posting Komentar

Postingan populer dari blog ini

Effect of Temperature on Resistance and Temperature-Coefficient of Resistance

Effect of Temperature on Resistance     we have explain erlier (Law of Resistance) that resistance of the conductor dipending on temprature. so that, here we will show you the effect of rise in temperature:     1) to increase the resistance of pure metal. The increase is large and fairy regular for normal ranges of temperature. The temperature/resistance graph is a straght line (figure 1).     2) to increase the resisrance of alloys, though, in their case, the increase is relatively small and irregular. for some high-resistance alloys like eureka (60% Cu and 40% Ni) and manganin, the increase in resistance is negligible ove a considerable range of temperature.    3) to decrease the resistance of electrolytes, insulators (such as paper, rubber, glass, mica, etc.) and partial conductors such as carbon. hence, insulators are said to prossess a negative temperature-coefisient of resistance. figure 1 ( The temperature/resista...
Posting Komentar
Baca selengkapnya

CONTACTOR USED TO CONTROL IN INDUSTRIAL

Contactor is an electromagnetic switch used to control any devise in industrila like electrical motors, lighting, heater, or other heavy load.  figure 1(contactors in spiral mixer) in operating system of contactor, it is devided in two parts:  --- power contactor (PC):  PC is the contact used power circuit, switch on or off electrical motor/lighting/heater/etc. Usually, a power contactor has 3 main contacts which shown figure 2 below.  --- auxiliary contactor (AC): AC is used    the contact used in control circuit, switch on off control system. Usually, auxiliary contact is consist of Normally Open (NO) and Normally Close (NC).   figure 2  (https://www.etman.no/) Part of contactor has special tagging according to IEC:  A1, A2    : is contacts of coil contactor 1, 3, 5      : is supply contacts in power circuit 2, 4, 5      : is load contacts in power circuit 13 ...
Posting Komentar
Baca selengkapnya

Modern Electron Theory

     Modern research has ebtablished that all matter whether solid, liquid, or gaseous, consists of minute particles called molecules which are them selves made up of still minute particles known as atoms. Those substances whose molecules consist of similar atoms  are known as elements (as shown in figure 1) Figure 1 (  http://gb.scientificgems.wordpress.com/) and those whose molecules consist of dissimilar atoms are called compounds (as shown in figure 2).  Figure 2 (https://prodiipa.wordpress.com/) An atom is taken to consist of the following:  1).  It has a hard central core known as nucleus. It contains two types of particlesor; one is known as proton and carries positive charge, the other is neutron (discovered by Chadwick in 1932), which is electrically neutral i.e. it carries no charge though it is as haevy as proton. The protons and neutrons are very closely held together with tremendous forces.  2). Revolving round...
Posting Komentar
Baca selengkapnya