Question

the resistance of a conducting wire of length one metre is 5 ohms calculate the resistance of the wire made by the same material whose length is 4 times and area of cross section is 5 times that of the wire​

Answer 1

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Given

length of a wire, L = 1m

resistance of a wire , R = 5 ohm

Applying resistance formula:

$\mathsf {R = \rho\frac{L}{A}}$

$\mathsf {5 = \rho\frac{1}{A}}$

$\mathsf {5 = \frac{\rho}{A}}$

$\mathsf {\rho = 5A}$

Since, the wire is made of same material

the resistivity will remain constant / same

Given,

New length of the wire, L' = 4L = 4m

New Area of the wire, A’ = 5A

let the new resistance be R'

Applying resistance formula:

$\mathsf {R' = \rho\frac{L'}{A'}}$

$\mathsf {R' = 5A × \frac{4}{5A}}$

$\mathsf {R' = 4 ohm}$

Answer 2

Answer:

4 ohm

Explanation:

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