Saved Bookmarks
| 1. |
A wire of resistivity G is stretched to 3 times its length what is the new resistivity |
|
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: |
|