I love reading articles about science experiments that you can do with simple household items. I ran across www.sci-toys.com some time ago while looking for information about the spectra of various types of lighting (incandescent, fluorescent, LED, etc.).
This article describes two spectroscopes, one using a CD or DVD as a diffraction grating, and one using the plastic film from those cardboard “rainbow glasses”. The article presents many photos like the one to the right, showing the spectrum produced by the sun, colored LEDs, flourescent lights, and other light sources. This photo clearly shows the bright spectral lines produced by the mercury vapor in the fluorescent light, and the broader spectrum produced by the phosphors that coat the tube.
This page has several other articles also related to light and spectra. There is an article describing how to make a more advanced high resolution spectrograph. The difference between a spectroscope and a spectrograph is that the latter records and analyzes the spectrum while the former just allows you to see the spectrum. Prior to the internet spectrographs were complex and expensive, but with digital photography and the internet they are cheap and easy. This article allows you to upload your spectrum photo and will return a graph of the spectrum. It is calibrated by uploading a reference spectrum from a fluorescent light with well known spectral lines and an additional spectra from another source.
The article on exploring invisible light has a terrific explanation of how fluorescence works, and exploring fluorescence in common objects such as flowers, currency, and turmeric. There is a recipe for invisible ink, and interestingly a link to purchase Kryptonite.
There are plenty more great articles and experiments here, covering magnetism, thermodynamics, biology, computers and electronics, and more. If your kids are too young to appreciate the experiments with light and optics then you can always build the solar hot dog cooker!
yours in simple science,