The HOT Chocolate Effect (Allassonic effect)
Channel: Kids Fun Science
Date: 2018-12-17

Made for parents and teachers
This experiment is called the Hot Chocolate Effect. You can do it yourself quite easily.

Filming equipment 
Cell Phone Tripod 54 inch Travel Tripod with Bluetooth Remote - https://amzn.to/34REzbB 
Blue Yeti USB Microphone - https://amzn.to/3ePJwGu 
Green screen & lights - https://amzn.to/2XT9Yc1 


Pour Cocoa mix in the cup and pour HOT water into the cup and then tap the rim of your mug several times with your spoon and listen to the pitch. Did it change while you were tapping? Probably Not!

Now this is where SCIENCE becomes FUN! Give it a couple of stirs and start tapping again. What do you hear? You should notice that the pitch frequency of your tapping gets higher and higher. Give it another stir and tap again. The pitch will go down and then rise again!

What’s the science behind it?
DRUM ROLL.....answer is BUBBLES. Adding powdered hot cocoa mix doesn’t just add a sweet chocolate flavor to your water, it adds tiny bubbles of air as well. As you stir in the chocolate you also mix the air bubbles into the liquid. All of those bubbles slow down the speed of sound in the hot chocolate. This lowers the frequency or the pitch of the sound waves that travel through the mug when tapped.

As the water spins around in the mug, the bubbles rise to the top and pop. With fewer bubbles in the hot chocolate, the speed of sound increases and the frequency does too so you hear a higher pitch.
Now stir it again and it dissolves more bubbles and it starts all over again!

The hot chocolate effect, also known as the allassonic effect, is a phenomenon of wave mechanics first documented in 1982 by Frank Crawford, where the pitch heard from tapping a cup of hot liquid rises after the addition of a soluble powder(Coca mix, instant coffee).

Hope you enjoyed this experiment. Please Like and SHARE. And thanks  for watching