You may have noticed while walking on a city street on a moonlit night that you have two shadows, one bluish and the other reddish. This phenomenon is explored and explained in a demonstration that can be set up easily.
A laser beam is made visible by the mist from a fog machine.
“One-way” mirrors are explored in an entertaining, hands-on experiment.
The half silvered mirror can produce deceptive reflections.
A small object appears to levitate above a hole. Will this illusion fool a cell phone camera? Remarkably a light appears to reflect off of the image!
The amazing lens bends the rays so the hole can be large and the image clear. Suitable for large lecture theatres with the use of a video camera.
Diffraction Grating Glasses
Inexpensive diffraction grating glasses are used to observe the spectra of many light sources.
Sulphur Dioxide Illusion
A cylindrical lens appears to invert the word SULPHUR but not DIOXIDE.
Water Stream Fibre Cable
Total internal reflection in a stream of water. See video below.
Total Internal Reflection in Prism
See the teacher though the prism. Related to binoculars, suitable for large lecture theatre with video camera.
Measuring Focal Length and Covering Half of a Lens
We first measure the focal length of a lens and then investigate what happens when we cover half of the object or half of the lens. With half of the lens covered we see the entire image dimmed.
For a simple two lens refractor telescope, the angular magnification is the ratio of the focal length of the objective lens to the focal length of the eyepiece. The lenses are placed a distance apart equal to the sum of their focal lengths and are then adjusted slightly as needed to focus.