Question

Why can't we hear the sound through a matchbox phone when the string is slack and again can hear it when the string is taut?

Answer 1

Dear student,


Lets say you took 2 match box, match box A on the speaker side and match box B on the receiving end. So when you speak into match box A it's base vibrates with your voice and those vibrations are then carried forward by the tight string in between and cause the base of match box B to also vibrate in the same way, thus conveying your message.
If the string is loose then the vibrations cannot travel through it. Think of a guitar string in this manner, would it oscillate if it was loosely bound?
I hope this was helpful enough.