Question

If the radius of cross-section of the conductor is increased by 0.1% keeping volume constant, then
change in the resistance of the conductor is
(1) -0.2%
(2) -0.1%
(3) -0.3%
(4) -0.4%​

Answer 1

Explanation:

Given If the radius of cross-section of the conductor is increased by 0.1% keeping volume constant, then  change in the resistance of the conductor is

In case of constant volume of a conductor, R α 1 / A^2

                                                     So R α 1 / (r^2)^2

                                                    So R α 1 / r^4

For any percentage change ΔR / R = - 4 Δ r/ r

                                                    = - 4 x 0.1 %

                                                   = - 0.4%

Reference link will be

https://brainly.in/question/3428927

Answer 2

The radius of cross section of the conductor is increased by 0.1 % the change in resistance of the conductor is - 0.4 %.

Step wise explanation is given below:

- As we know that the formula of resistance = Resistivity× Length/Area.

- Resistance is directly proportional to length and inversely proportional to area and the resistivity depends upon the nature of the material as mentioned in the question the volume of the wire is constant so the resistivity will be constant .

- Here, as per the question there is increase in the radius of the wire by 0.1%

( A ) = π r 2

- R= (ρ) L/A^2

= (ρ) L/(r^2)^2

= (ρ) L/r^4

- For any percentage change

ΔR/R = - 4Δr/r

= -4× 0.1%

= - 0.4%

- So,option (4) is the correct option.