Question

What is resistivity and its SI unit? Form an equation for resistivity?

Answer 1

Answer:

si unit of resistivity is ohm×meter

Explanation:

R=p l/a=

p=R×a/l

p=ohms×m²/m=ohms×m

Answer 2

Resistivity :

• It's defines as the resistance of a conductor of unit length and unit area of cross section.

• Its SI unit is ohm - metre.

• The resistivity of a material doesn't depend on its length or thickness but depends on the nature of the substance and temperature.

• It's a characteristic property of the material of the conductor and varies only, if its temperature changes.

• Insulators such as glass , rubber , ebonite, etc. have a very high resistivity while conductors have a very low resistivity.

• Alloys have higher resistivity than that of their constituent metals.

• They don't oxidise easily at high temperatures, this is why they're used to make heating elements of devices like electric iron , heaters , etc.

• Tungsten is almost used exclusively for filament of electric bulbs, whereas copper and aluminium are generally used for electrical transmission lines.

• R varies to length / area of cross section.
• R = rho × length / area of cross section ; where Rho is the constant of proportionately and is called resistivity or specific resistance of the conductor.