The length of a metal wire is l1 when the tension in it is T1 and is l2 when the tension is T2. The natural length of the wire is
The correct option is
C
Let the Area of cross-section of the wire be 'S' and it doesn't' vary as the length changes within the elastic limit.
In the first case, the elongation in the wire=l2−l
⇒Y1=(T1s)l(l1−l)
Now,the second case, the elongation in the wire =l2−l
⇒Y2=(T1s)l(l1−l)
Now, Y1=Y2 as the material is same
⇒T1ls(l1−l)=T2ls(l2−l)
⇒T1l1−l=T2l2−l
T1l2−T2l=T2l2−T2l
l(T2−T1)=T2I2−T1I2
l=T2l1−T1l2T2−T1