We’re deep in the course of winter right here, which implies we’ve been taking the chance to study all issues chilly, darkish and snowy. And in order a part of our polar research, we made this tremendous cool Northern Lights tray, which doubles as a science experiment on water floor stress (extra on that later).
Create the Magic of the Northern Lights
First, you have to some form of shallow tray or plate. A round-shaped tray works finest.
Subsequent, pour in some milk (you need to use expired when you have it!), sufficient to cowl the underside and an inch or two excessive. Place a number of drops of meals coloring on the floor of the milk. You should use completely different colours (we used frequent aurora colours like inexperienced, blue, purple, and so forth.)
Subsequent, get out some Q-tips and a bit of cup or dish containing dish cleaning soap. You don’t want a whole lot of cleaning soap, simply sufficient in an effort to dunk your Q-tips in.
Now, watch the magic occur. Instruct your college students to faucet every dot of meals coloring with a soap-coated Q-tip, and watch the northern lights seem! ✨
You’ll be able to proceed so as to add meals coloring and repeat this exercise so long as you would like, though the milk will proceed to get darker and darker. It truly is cool to observe – your college students will wish to do that many times!
We paired this exercise with some printed pages from our Arctic Journal, together with some great books in regards to the Aurora Borealis.
The Science Behind It
We did this exercise together with our research of the polar night time and the arctic circle, BUT I’ll by no means go up a chance to debate how issues work – and this little exercise is a good way to kick off speaking a couple of phenomenon often called floor stress.
What’s floor stress?
Floor stress is outlined as the strain of the floor movie of a liquid attributable to the attraction of the particles within the floor layer by the majority of the liquid.
In different phrases, the molecules on the floor of a liquid (like milk) are pulled extra tightly to one another than the molecules beneath the floor. This unseen drive is named floor stress, and it ends in a “pores and skin” on the floor of a liquid, permitting it to withstand exterior forces. (Take into consideration pond skaters on the floor of the water.)
The floor stress of the milk retains the meals coloring drops from spreading. When the dish cleaning soap is added, it binds to the fats molecules within the milk, decreasing the floor stress. For this reason it seems like the colours are “operating away” from their level of origin.
You’ll be able to repeat this experiment with plain water, black pepper and a toothpick dipped in cleaning soap. Fill a shallow container with water, as an alternative of milk, and pour in some black pepper. Have your college students faucet the floor of the water with a toothpick coated in cleaning soap, and watch the pepper scurry away!
Need to train your children extra in regards to the northern lights and the polar night time? Take a look at our new Arctic Journal!
