Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Have ever noticed? When water is about to boil, no matters the kettle, there is some sound I have no idea where it comes from, sometimes long before it boils.

Is there any explanation for this phenomena?

share|cite|improve this question
up vote 6 down vote accepted

The water near the heating element turns into water vapor. This vapor then rises up to the surface but as it meets colder water upwards it turns back into water.

As the water/steam transition is not smooth (e.g. the volume changes rather rapidly during phase change), the constant transition between vapor and liquid states produces noise. As the water gets to +100C (boiling point), the vapor bubble will not turn back into liquid before reaching the surface thus making less noise.

For more on this click this.

share|cite|improve this answer
It can even be seen, when you have a translucent electric kettle. – mbq May 1 '11 at 10:20

I don't know how good this explanation is, but it is certainly plausible. The sound must be from bubble formation/popping. It seems the difference between the noise in the beginning and when the water is really boiling well is because in the initial phase, bubbles don't reach the surface.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.