Resistivity of the wire depends on mainly ___________

Question

Question

This question was previously asked in

RRB ALP Instrument Mechanic 23 Jan 2019 Official Paper (Shift 1)

Answer 1

Explanation:

Resistivity (ρ)

From Resistance,

\(R = \rho \frac{l}{A}\)

Where R = resistance, l = length, A = area of cross-section and ρ = resistivity

If l = 1 m and A = 1 m2, then

R = ρ i.e.

Resistivity is numerically equal to the resistance of a substance having a unit area of cross-section and unit length.
Resistivity is the intrinsic property of the substance. It is independent of the shape and size of the body i.e. on length and area. Hence, option 1 and 2 is incorrect.
Formula of resistivity is \(\rho = \frac{m}{{n{e^2}\tau }}\)
Where, m = mass of electron, n = Number of electrons per unit volume of the conductor, τ = relaxation time.
Therefore, the resistivity of a wire depends on its material (n)
For different substances their resistivity is also different as ‘n’ will be different.
Resistivity depends on the temperature.