Question

There are two wires A and B of same material. A is 20 times longer than B and has one fifth of cross sectional area as that of B. If the resistance of A is one ohm, what is the resistance of B?

Answer 1

Explanation:

pls see the attachment

Answer 2

Answer:

Resistance of B has hundred times of Resistance of A

Explanation:

We have been given,

A is 20 times longer than B,

L₁ = 20 L

L₂ = L

And A is one fifth of cross sectional area of B,

A₂ = 5 A

A₁ = A

Resistance of  R₁  = 1

Now ,

Resistance  R = $\rho\dfrac{L}{A}$

$\dfrac{R1}{R2}=\dfrac{L1*A2*\rho}{L2*A1*\rho} \\\\\dfrac{1}{R2}=\dfrac{20*5}{1*1}\\R2 = \dfrac{1}{100}\\R2 =\dfrac{R1}{100}$

Correct answer  = Resistance of B has hundred times of Resistance of A