 Welcome back to Kids Fun Science. My name is Ken. Today's experiment is the hot chocolate effect. As always, adult supervision is required. What you need for this experiment is hot water, a cup, a spoon, and some hot cocoa mix. This experiment is called the hot cocoa effect. You can do it yourself quite easy. So go ahead and take your hot cocoa mix and pour it into the cup. This experiment wasn't really discovered until 1982. Then take your hot boiling water and pour it into your cup. Then what you're going to do is take your spoon on the mug and tap it several times and listen to the pitch, which it shouldn't change. So here's where it becomes fun. So give it a couple swirls and then start tapping again and see what you hear. You should notice the pitch of the frequency. The tapping gets higher and higher. Go ahead and give this hot chocolate a swirl a couple times and start tapping it again. You should still hear the pitch start to go up again. So the science behind this is the answer is bubbles. Adding the powder hot chocolate doesn't just add sweet chocolate flavor to your water. It adds tiny bubbles of air as well. So when you stir the hot chocolate, you'll also mix the air bubbles in the liquid. Then all those bubbles slow down the speed of sound in the hot chocolate. So this lowers the frequency or the pitch of the sound waves as it travels through the mug when it's tapped. As the water spins around the mug, the bubbles rise to the top and pop. With fewer bubbles, the hot chocolate, the speed of the sound increases and the frequency does too and you hear a higher pitch. I hope you enjoyed this experiment. Please like and share and thanks for watching.