Waves and Sound question bank (Physics)

A sonometer wire vibrating in two loops is in resonance with a tuning fork. If tension applied to the string is increased to 16 times the original tension and length of the wire is doubled. It can still be in resonance with the tuning fork provided it vibrates in

A pipe closed at end vibrating in the fourth overtone is in unison with the open pipe vibrating in its fourth overtone. The ratio of $l_c : l_o$ is {$l_c$ = vibrating length of closed pipe, $l_o$ = vibrating length of open pipe}