Question

"A cylindrical conductor of length ‘l and uniform area of cross-section ‘A’
has resistance 'R'. Another conductor of length 2.5 l and resistance 0:5 R
of the same material has area of cross-section​

Answer 1

Explanation:

u follow the rule of R= pl/A

answer is 5A.

Answer 2

The area of the cross section of the material is 5 times of the initial area.

Explanation:

A cylindrical conductor of length l and uniform area of cross-section A  has resistance R. The resistance of the conductor is given by :

$R=\rho\dfrac{l}{A}$...........(1)

Another conductor of length 2.5 l and resistance 0.5 R  of the same material. New resistance is given by :

$0.5R=\rho\dfrac{2.5l}{A'}$........(2)

Dividing equation (1) and (2). We get :

$\dfrac{R}{0.5R}=\dfrac{(l/A)}{(2.5l/A')}\\\\2=\dfrac{2A'}{5A}\\\\A'=5A$

So, the area of the cross section of the material is 5 times of the initial area.

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