Question

a uniform wire of resistance R is stretched so that its radius becomes 3/4 of its original value.What is the new resistance?

Answer 1

Answer:Volume will remain same:

So, Initial volume = Final volume

Pi*r*r*l = pi*0.75r*0.75r*new length

New length = 16*l/9

New resistance = rho*l/A

= rho*16l/ (9*pi*0.75r*0.75r)

= R' * 256/81

Explanation:

Answer 2

256R/81 is the ideal answer.

Given:

• The uniform wire of the resistance = R,
• After stretching its radius will become 3/four of its authentic value.

To find:

• The new resistance =?

Explanation:

• V =πr²l ⇒ l = V/πr².
• R = ρl/A ⇒ ρV/(πr²)².
• R1/R2 = (r2/r1)⁴ = (3r/4r)⁴ = (3/4)⁴.
• R2 = R(4/3)⁴ = 256R/81.

Therefore, the new resistance is 256R/81.

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