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sesenic [268]
3 years ago
13

The length of a certain wire is doubled and at the same time its radius is also doubled. What is the new resistance of this wire

Physics
1 answer:
Leto [7]3 years ago
4 0

Answer:

R' = R/2

Therefore, the new resistance of the wire is twice the value of the initial resistance.

Explanation:

Consider a wire with:

Resistance = R

Length = L

Area = A = πr²

where, r = radius

ρ = resistivity

Then:

R = ρL/A

R = ρL/πr²   --------------- equation 1

Now, the new wire has:

Resistance = R'

Resistivity = ρ

Length = L' = 2 L

Radius = r' = 2r

Area = πr'² = π(2r)² = 4πr²

Therefore,

R' = ρL'/πr'²

R' = ρ(2 L)/4πr²

R' = (1/2)(ρL/πr²)

using equation 1:

<u>R' = R/2</u>

<u>Therefore, the new resistance of the wire is twice the value of the initial resistance.</u>

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