Question

derive the formula for resistivity (2mark)(maybe mathematically)​

Answer 1

Answer:

Thus, Resistance (R) ∝ length of conductor (l)

or

R

∝

l

--------(i)

Area of cross section: Resistance R is inversely proportional to the area of cross section ( A) of the conductor. This means R will decrease with increase in the area of conductor and vice versa. More area of conductor facilitates the flow of electric current through more area and thus decreases the resistance. This is the cause that thick copper wire creates less resistance to the electric current.

Thus,

resistance

∝

1

Area

of cross section of conductor (A)

Or,

R

∝

1

A

---------(ii)

From equation (i) and (ii)

R

∝

l

A

Or,

R

=

ρ

l

A

-----------(iii)