A rigid bar of mass M is supported symmetrically by three wires each of length l . Those at each end are of copper and the middle one is of iron. The ratio of their diameters, if each is to have the same tension, is equal to
1
Ycopper/Yiron
2
\(\sqrt {\frac{{{Y_{iron}}}}{{{Y_{copper}}}}} \)
3
\(\frac{{Y_{iron}^2}}{{Y_{copper}^2}}\)
4
\(\frac{{{Y_{iron}}}}{{{Y_{copper}}}}\)