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Two wires A and B are of the same material. Their lengths are in the ratio 1 : 2 and the diameter are in the ratio 2 : 1. If they are pulled by the same force, then increase in length will be in the ratio
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- 2 : 1
- 1 : 4
- 1 : 8
- 8 : 1
Correct Option: C
We know that Young's modulus
Y = | × | ||
πr² | l |
Since Y, F are same for both the wires, we have,
= | |||||||
r1² | l1 | r2² | l2 |
or, | = | = | mv² | |||
l2 | r1² × L2 | (D1/2) × L2 |
or, | = | = | × | = | |||||
l2 | D1² × L2 | (2D2)² | 2L2 | 8 |
So, l1: l2 = 1 : 8