Sn (tin) is a metal, and Si (silicon) is a semiconductor. The key difference lies in the energy band gap between the valence band and the conduction band.
- In metals like Sn, the energy gap between the valence and conduction bands is negligible or practically zero, meaning electrons can move freely to the conduction band at room temperature, allowing Sn to conduct electricity easily.
- In semiconductors like Si, there is a small but non-zero energy gap (about 0.07 eV) that separates the valence band and conduction band. This small energy gap allows Si to conduct electricity under certain conditions (e.g., at higher temperatures or when doped with other materials).
Thus, the correct reason for Sn being a metal and Si being a semiconductor is the difference in their energy gaps, with Sn having no significant gap.
If the ratio of lengths, radii and Young's Moduli of steel and brass wires in the figure are $ a $, $ b $, and $ c $ respectively, then the corresponding ratio of increase in their lengths would be: