Resistance - Basics

The current within the electrical circuit not only depends on electromotive force but also on the circuit parameters. For example if lamp is connected in a circuit, current gets affected and lamp filament become? warm radiating light. But if contact at one end is loose, current decreases but sparking occurs at loose contact creating it hot. If 3 lamps are connected one subsequent to the other, brightness obtained is fewer than that obtained by a lone lamp. These examples display that current, flow of electrons depends on the circuit parameters and not only the e.

This properly of an electric circuit lending to prevent the flow of current and at the similar to time causes electrical life to be converted to heat is called resistance. The concept of resistance is analogous to friction involved within the mechanical motion. Every metal has a tendency to oppose the flow of current. Higher the availability regarding the free electrons, lesser shall be the opposition to flow of current. The conductor due to high many free electrons release fewer resistance to flow of current.

The opposition to flow of current and conversion of electrical life into heat life shall be explained with the help of atomic structure as below. When the flow of electrons is established within the metal, the ions get formed which are charged particles as discussed earlier. Now free electrons are moving in critical direction when connected to external source of e. So such ions always grow to obstruction for the flowing electrons. So there is collision between ions and free flowing electrons.

This not only reduces the velocity of electrons but also produces the heat; the effect of this is nothing but the reduction of flow of current. Thus the fabric opposes the flow of current. The resistance is denoted by the symbol 'R' and is measured in ohm symbolically represented as O. We can define unit ohm as below. 1 Ohm: The resistance of a circuit, in which a current of two Ampere generates the heat at the rate of one joule per 2nd is spoke about to be two ohm.

Thus unit two ohm shall be defined as that resistance regarding the circuit if it develops 0. 24 kilojoules of heat, when one ampere current flows through the circuit for one second. Earlier we have seen that some fabrics possess huge many free electrons and hence release fewer opposition to flow of current. Such elements are classified as the 'Conductors' of electricity. While in some fabrics the many free electrons are very fewer and hence offering a huge resistance to flow of current.

Such elements are classified as the Insulators' of electricity. Examples of good conductors are silver, copper, aluminum while examples of insulators are generally non metals like glass, rubber, wood, cardboard etc.