Question

A wire of length L and resistance R is stretched so that its length it doubled. how will the(1) resistance change (2) resistivity change




please answer my question​

Answer 1

Answer:

(1) the resistance is doubled.

(2)the resistivity does not change .

Explanation:

resistance is proportional to the length

but resistivity does not change if the length of the wire is changed.

Answer 2

Question :-

A wire of length L and resistance R is stretched so that its length it doubled. How will the (1) resistance change (2) resistivity change

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Solution :-

Resistance = ρl/A

Where,

ρ = resistivity

l = length

A = cross sectional area

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A/Q

(i) Given :-

Length is doubled = 2L

Area of cross section = A/2

$\sf New \: resistance( R')\:=\: \rho\frac{2l}{\frac{A}{2} } \\R' \: = \: \rho\frac{2l\:\times2}{A} \\R' \: = \: \rho\frac{4l}{A} \\R' \: = \: \frac{4\rho l}{A} \\R' \: = \: 4R$

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Therefore, new resistance is 4 times the original resistance.  

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(ii) Resistivity depends on temperature and nature of material hence there won't be any changes.