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Inquiry 8: How Does It Work? Binoculars, Periscopes, and Kaleidoscopes
Binoculars
Binoculars are really just two refracting telescopes joined together with a hinge. Soon after telescopes were invented, people started to fasten two of the long tubes together to make binoculars. These long binoculars, however, were heavy and difficult to handle. Since it was difficult to keep these tubes parallel to one another, the image seen was often doubled.
Around 1900 a German physicist named Ernst Abbe made a pair of binoculars using prisms that reflected the incoming light twice. This meant that it was possible to make a shorter instrument. Also, by using two prisms the image that formed appeared right side up.
Binoculars are currently found in three designs: 6x30, 7x50, and 8x30. The first number refers to the magnification of the binoculars and the second number gives the diameter of the objective lens in millimeters. When using binoculars, you look at an object and light reflects off the object and enters the front of the binoculars through the objective lens. This forms an image that is upside down and reversed. Prisms correct the image before we see it through the magnifying eyepiece lenses.
Life Science - Use binoculars to observe birds. Record some of the following features used for the identification of birds: the shape and color of the eyes, feet, color of the plumage, shape of the head, shape of the tail feathers, and beak shape and color. You may also want to sketch what you observe. Then, using guidebooks for the identification of birds, try to determine what kind of birds you were watching.
Periscope
Periscopes are instruments that allow the viewing of objects that are not in the direct line of vision. They are often found in submarines and may have tubes up to 10 meters long. Tanks also contain periscopes that allow people inside of a tank to view the surrounding area while remaining protected inside of the vehicle. The development of fiber optics led to the development of other types of periscopes that allow doctors to view inside the human body without having to perform major surgery. These types of periscopes are called endoscopes or cystoscopes and are very useful in the medical field.
Make a Periscope - Construct a periscope by using the directions that follow. This activity will allow you to experiment with mirrors and the correct placement of them in the scope.
Required Materials
- 2 empty quart-sized cardboard milk or juice containers
- 2 small rectangular mirrors, mirror paper, or Mylar
- Tape
- Scissors or a craft knife
- Science notebook
Activity Directions
Cut the tops off of two milk cartons.
Cut a hole about 5 cm in diameter in one side of each carton near the bottom.
Tape a mirror, tilted at a 45-degree angle, in the bottom of each carton, with the shiny side facing the hole.
Tape the two cartons together so that the holes are on opposite sides of the periscope. In other words, where you look into the periscope is on the opposite side of the tube from the hole where light is coming in.
Answer the following questions in your science notebook:
What do you see when you look into the periscope?
How could you use your periscope?
Have you ever seen a periscope used? Or, have you seen another instrument that works like a periscope?
How can you improve upon the design of your periscope?
Kaleidoscope
The kaleidoscope was invented by Sir David Brewster around 1816 and patented the following year. The device uses the image-forming properties of combined inclined mirrors. Depending on the number of mirrors and the angle between them, the kaleidoscope will produce multiple symmetrical patterns. Since its introduction, the kaleidoscope has been sold primarily as a toy, but has practical uses as well.
A simple kaleidoscope is made of two thin, wedge-shaped mirror strips touching along a common edge or a single sheet of bright aluminum bent to an angle of 45 or 60 degrees. The mirrors are enclosed in a tube with a viewing eyehole at one end. At the other end is a thin, flat box that can be rotated. This flat box is made from two glass disks, the outer one ground to act as a diffusing screen. In this box are pieces of colored glass or beads. When the box is turned or tapped, the objects inside tumble into different groups and when the diffusing screen is illuminated by natural or artificial light, six or eight different symmetrical images appear. The number of combinations and patterns is without limit.
There are five different types of kaleidoscopes. The chamber kaleidoscope has an enclosed object case with free-tumbling jewels, glass, beads or other objects. The liquid chamberscope has an object case filled with liquid (usually glycerin) in which the jewels, glass beads, or other objects float. The wheel scope has one or more wheels at its objective end that may contain glass, translucent rocks like agates, pressed flowers, beads, jewels, or other objects. The refillable scope features a removable object chamber. The contents of this chamber can be changed and users can experiment with their own assortment of colors and objects. The teleidoscope uses mirrors and lenses alone so that anything that is viewed, is multiplied.
Make a Pringles Can Kaleidoscope - Design your own kaleidoscope out of a Pringles can with the following directions.
Required Materials
- Pringles can
- Nail and hammer
- Scissors and compass
- Transparency film
- Black construction paper
- File folder
- Glue
- Pen and ruler
Activity Directions
Make a hole in the center of the metal bottom of the Pringles can with the hammer and nail. With the point of the scissors or other object, expand the hole to a 1.5 cm diameter. This will be the eyehole of the kaleidoscope so it is important that there are no sharp edges.
Cut out a 4 cm square of transparency film. Glue the transparency square over the eyehole of the kaleidoscope.
Cut from the file folder three 7.5 cm x 19.5 cm strips. Do the same with the black construction paper and the transparency film.
Glue the strips together in the following order: file folder, black construction paper, and then transparency film. You should now have 3 sets of layered strips. The transparency on top of the black paper should provide a mirror-like surface.
Place each set of strips into the open end of the can, edge to edge, with the mirror surfaces facing the center of the can. Looking into the can, the top edges of the strips should form an equilateral triangle.
Cut 2 strips from the file folder (23 cm x 1.5 cm). Fold one strip in half the long way. Glue the folded strip along the long edge of the unfolded strip.
Glue the combined strips around and along the inside edge of the open end of the can above the mirrors. The folded strip should be closest to the mirrors. Let the glue dry.
Cut a circle of transparency film with a diameter of 7.5 cm (the same diameter as the opening of the can).
Place the transparency circle inside the open end of the can with its edge against ledge created by the folded strip. Glue the circle in place with rubber cement.
Place various objects (beads, shells, gemstones, etc.) on top of the transparency circle. Place lid of can back on.
Your kaleidoscope is done! Look through the eyehole while turning the can and see the kaleidoscopic show.
Make a Paper Towel Roll Kaleidoscope - Design your own kaleidoscope out of a paper towel roll with the following directions.
Required Materials
- Paper towel roll
- Scissors and compass
- Masking tape and glue
- Pen and ruler
- Black construction paper
- Transparency film
- File folder
Activity Directions
Trace the top of the paper towel roll on the folder. Using a compass, draw a circle 1.5 cm larger around the circle you traced. Cut out the larger circle.
Make a hole about 1.5 cm in diameter in the center of the circle. This will be the eyehole for the kaleidoscope.
Make small cuts around the outer edge of circle from the edge to the traced line. The cuts should be made about every 1.5 cm around the circle. The cuts will form little tabs around the edge of the circle.
Cut out a piece of transparency film large enough to cover the eyehole. Glue it over the eyehole.
Place the circle on the one end of the roll with the transparency piece facing inside the roll. Fold down the tabs all around the outside of the roll. Secure it to the roll with masking tape.
Cut from the file folder three 6.5 cm x 27 cm strips. Do the same with the black construction paper and the transparency film.
Glue the strips together in the following order: file folder, black construction paper, and then transparency. You should now have 3 sets of layered strips. The transparency film on top of the black paper will provide a mirror-like surface.
Place the strips side-by-side, mirrored surface down, on top of your work surface. Put masking tape across the strips at the top and bottom.
Fold the connected strips to form a three-sided column 27 cm long with the mirrored surface facing inside. Tape around the column to hold it together. Looking into the column, the top edges of the strips should form an equilateral triangle. Place the column into the open end of the tube.
Cut out two circles from the transparency film using the directions in steps 1 and 4. You should now have two circles of transparency film with 1.5 cm tabs around it.
Fold back the tabs of one of the transparency circles then place it into the open end of the tube so the circle is touching the mirrored column and the tabs are facing out. Secure the circle to the tube with tape.
Place your choice of colorful objects (beads, gems, rocks, etc.) into the open end of the tube.
Now place the other transparency circle over the open end of the tube. Fold down the tabs all around the outside of the roll. Secure it to the roll with masking tape.
Your kaleidoscope is done! Look through the eyehole while turning the tube and see the kaleidoscopic show.
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