Question

A current of 3A flows throughs a metal rod of diametes 0.2 mm and lengths 1.5cm when a potential difference of 40 v is applied. The resistivity of material is​

Answer 1

Answer:

0.001 is the resistivity

Answer 2

Given - Current : 3 Ampere

Diameter of wire : 0.2 mm

Length of wire : 1.5 cm

Potential difference : 40 volt

Find - Resistivity of material

Solution - Resistivity of material is calculated by the formula - rho = R*A/L. Here, rho is resistivity, R is resistance, A is area and L is length.

Diameter of wire in metre = 0.0002

Length of wire in metre = 0.015

Cross sectional Area of wire = (π*d²)/4

Cross sectional Area of wire = (π*0.0002²)/4

Cross sectional Area of wire = 3.14*10^-⁸ metre².

Resistance of wire = Potential difference/Current

Resistance of wire = 40/3

Resistance of wire = 13.3 ohm

Keeping the values in the formula-

Rho = (13.3*3.14*10^-⁸)/0.015

Rho = 2.78*10^-⁵ ohm metre.