1
vote
2answers
66 views

what could generate a high-pitched whine in electronics where the frequency depends on the current?

So I was operating a Laue machine recently which generates x-rays and fires them at a sample, and I noticed that there was a high-pitched whine coming from the instrument (nothing abnormal, just ...
5
votes
1answer
272 views

Whistling on bottle tops

It is well known that if you blow horizontally on a bottle top it creates a sound. Pouring water to the bottle changes the pitch. I have been doing experiments on the relation between the sound's ...
3
votes
1answer
282 views

Why is there a hiss sound when water falls on a hot surface?

Why is there a hiss sound when water falls on a hot surface? I have searched a lot, asked my teachers but none of them seem to give me the logical answer to it.
5
votes
3answers
586 views

Why echos cannot be heard inside the room?

If I go camping and shout anywhere, in the forest , or on a cliff, I usually hear the echo of my voice. Why when I shout in my room I do not hear any echos?