On keeping the stem of a vibrating tuning fork on the surface of a table, a loud sound is heard. Give reason.

When the stem of a vibrating tuning fork is pressed against the top of a table, the forced vibrations are produced on the surface of table.

The table top has a much larger vibrating area than the tuning fork, so the forced vibrations of the table top send forth a greater energy and hence, produce a larger sound ( or more intense ) than that produced by the fork.