Question

a wire of resistivity G is stretched to 3 times its length what is the new resistivity ​

Answer 1

Answer:

When wire is stretched 3 times of its original length, its resistance will increase 9 times, because when length increases radius decreases i.e. area decreases. But volume i.e. area × length remains same .

Let A1 & A2 be original and new areas and let l1 and l2 be original and new lengths

A1×l1 = A2×l2

A1/A2 = l2/l1

Let R1 be original resistance and R2 be new resistance

R=(resistivity × length )/area

Taking ratio of R2 to R1,

(R2/R1) = (A1/A2) ×(l2/l1)

Putting (A1/A2) = (l2/l1)

(R2/R1) = (l2/l1))^2

If l2 = n × l1

R2/R1 = n^2

R2 = n^2 × R1

In general if length increased n times , resistance increases n^2 times.

Resistivity is property of material, it do not change with change in dimensions. Therefore resistivity will remain the same.

Hope understood.

Explanation:

Answer 2

Answer:

Hope this helps you

Explanation:

When wire is stretched 3 times of its original length, its resistance will increase 9 times, because when length increases radius decreases i.e. area decreases.