Resistance

It is the property of a substance which restricts the flow of electric current. In the article we will discuss about resistance, factor affecting resistance and affect of temperature on resistance.




We know that current is the flow of electrons, hence resistance is an opposition to the flow of electrons. This opposition occurs due to presence of large number atoms and molecules.

When current flows through a substance, the free electrons move through the material and collide with atoms and molecules. These collisions cause the electrons to lose some of their energy and it also offer opposition to the flow of electrons. The atomic structure of the substance decides the extent of opposition.

Silver, copper and aluminum offer least resistance to flow of current. Tungsten, Nichrome offer very high resistance to flow of current.

The unit of Resistance is ohm follow ( Multipli e sottomultipli del Sistema Internazionale e prefissi dei multipli http://www.mcmp.cz/biorefre/1643 الخيارات الثنائية نسخة تداوله في المملكة المتحدة ), denoted by ücretsiz forex demo R.

symbol of resistance

yetkili forex firmaları Factor Affecting Resistance

Resistance of a conductor depends upon the following factors

source link Length

Resistance of conductor is directly proportional to the length of the conductor. Greater the length, greater the resistance and vice versa.

http://havanatranquility.com/daeso/6646 R α l ……………….. (i)

get link Area of Cross Section

Resistance of conductor is inversely proportional to the area of cross section of the conductor. Greater the area of cross section, lesser the resistance and vice versa.

http://missionnorman.org/emiios/5779 Nature of Material

Resistance of the conductor depends upon the nature of the composition of the material of which the conductor is made up. Difference substances have different atomic structures and therefore, offer different resistances for the same length and area of cross section.

binary option strategies for nadex\'A=0 Temperature

The resistance of the conductor depends upon the temperature of the conductor. The resistance of the conductor increases with increase in temperature.

From equation (i) and (ii), we get

factor affecting resistance

Where ρ (Rho) is constant of proportionality and it’s called resistivity or specific resistance of the material. P (Rho) refers to the nature of material.




follow link Effect of Temperature on Resistance

The resistance of metals increases with increase in temperature. The graph plotted between temperature and resistance is straight line. The metals have positive temperature co-efficient of resistance.

  • For Alloys

The resistance of alloys increases with the increase in temperature but the increase is very small and irregular.

  • For insulators, electrolytes, semiconductor etc

The resistance of insulators, electrolytes and semiconductors decreases with the rise in temperature. These materials have negative temperature co-efficient of resistance.



 

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