A) \[\frac{l}{2}\]
B) \[l\]
C) \[2l\]
D) 4L
Correct Answer: B
Solution :
From Hookes law, the ratio of longitudinal stress to cores-ponding longitudinal strain is known as Youngs modulus of the material of wire. \[Y=\frac{stress}{strain}=\frac{F/A}{l/L}=\frac{F/\pi {{r}^{2}}}{l/L}\] \[Y=\frac{F}{\pi {{r}^{2}}}\frac{L}{l}\] Given, \[{{L}_{2}}=2L,\,{{r}_{2}}=2r\] \[\therefore \] \[{{Y}_{2}}=\frac{2F}{\pi {{(2r)}^{2}}}.\frac{2L}{l}=Y\] Hence, change in length is same as the original.You need to login to perform this action.
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