Surely, all of your students have observed the way light reflects water somewhere outside of the classroom.* It’s a pretty neat effect to see with one’s own two eyeballs, but a more controlled view of this effect will help them better learn about how light and water interact. This Demo Science science demo is just the thing!
Like Oil & Water
For this experiment, you’ll need vegetable oil, water, and a magazine. I can be any magazine you like, but I recommend Miniature Donkey Talk. It is a world class periodical.
Gather your students ‘round your desk—hopefully they can all fit without somebody throwin’ ‘bows. Tear a page from your magazine (be sure to use an issue you’ve already committed to memory) and, using your finger, dab a dab of vegetable oil on one word on the page. Any word will do, but be sure to keep it relatively short—“rhododendron”, pleasant as the word may be, is not an ideal choice here.
Rub the oil in and let it set for just a second. Make sure your students all get a good look. Then, using a different finger, drop a drop of water onto the oil-covered word. What happens?
By the Watery Lens of Neptune!
Looking at the printed word through the water makes it appear larger. This is because, as the two don’t mix, the water sits on top of the oil you rubbed into the page, forming a kinda sorta lens. The image of the word underneath appears larger and wider.
The same general principle is used to make lenses for eyeglasses. With eyeglasses, glass or plastic is used to bend the light in a specific way, allowing it to reach the wearers’ eyes at the correct angle to improve their vision.
* They have. And don’t call me Shirley.