Question

On what factor the resistance of a conductor depends give its mathematical expression. Give the SI unit of resistivity?

Answer 1

Explanation:

Resistance of a conductor depends on length of the conductor ,area of cross section of the conductor ,nature of the material of the conductor and temperature of the conductor.

Resistance is directly proportional to length resistance is inversely proportional to area of cross section.

only for the case of resistances which are made up of pure metals resistance is directly proportional to temperature.

the SI unit of resistivity is ohm m

Answer 2

Answer:

Resistance depends on resistivity (directly proportional) ,

length of the conductor through which current is passing ( directly proportional)

and area of the conductor through which current is passing (inversely proportional)

also depends on material of the conductor becoz resistivity depends on material of the conductor.

R = (rho × length) ÷ area

also the resistance depends on the temperature

mathematical expression is

Rt = Ro × ( 1 + alpha × delta T)

Rt is the resistance at final temperature

Ro is the resistance at initial temperature

alpha is the temperature coefficient

delta T is the chage in temperature

so resistance depends on temperature.

si unit of resistivity is ohm metre

rho= ( R × A )/ length

rho =( ohm × metre^2 ) / metre