Age level: 8-18 years
Group of students: 3 or 4 per group
Time: 60 minutes
Objective: Learn about periscope and optical devices using Engineering design process.
Periscope are used to see objects which are not at the same level as of observer. Light from the object falls on one mirror and is reflected. This reflected light in turn falls on another mirror and is again reflected until it reaches human eye. It lets you see over the top of things such as fences or walls that you aren't tall enough to look over. People first started using periscope in submarine to allow sailors to see above the water.
Inside the periscope there are two mirrors or prisms that are placed in parallel and facing each other. The mirrors are placed at 45 degree angle.Principle of periscope is based on laws of reflection. According to laws of reflection, when a ray of light falls on a plane surface it gets reflected at an angle equal to the incident angle.
Engineering design process:
Ask: To build a periscope that can be used to identify series of objects that are out of direct sight.
Imagine: They can brainstorm ideas
1.What should be the shape of periscope, box type or cylindrical type?
2.Which idea is most useful?
3.What material can be used?
Plan and create: Students can select the best idea they think is appropriate and start making periscope.
Test: To see how the design worked.
Improve: Design may fail or succeed during testing. They must be encouraged to improve their model.
Majority periscope on the internet are box type. But i have designed a cylindrical type periscope which is easy to make.
5. Thick paper A3 size sheet
6. Square Mirror 7x7 cm
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Step 1: Housing the Mirror
1.Take any cardboard piece of 20 cm length and 10 cm breadth.
2.Fold half of the section as shown.
3. Using a circle cutter, cut a circle of 6 cm diameter. This circle will act as hole to view the mirror placed.
4. Make slits on the sides of the rectangular section.
Step 2: Top and Bottom Section of Periscope
1. In other cardboard piece, draw a triangle using set square of 45 degree. Also, make tabs along the sides as shown.
2. Cut half of the triangular section and glue the tabs.
3. Fit the half cut triangular section in the slits of the rectangular section made in step 1.
Similarly make another section. Thus, you will have top and bottom section ready.
Step 3: Join Parts of Periscope
1. Fold a thick sheet of paper into cylindrical shape.
2. Insert the ends of cylinder to the top and bottom section of periscope.
3.Tape the cylinder.
4. Glue and fix the top and bottom section.
5. Take a square 7 x 7 cm mirror. Glue the back of mirror and place on section as shown in the image.
Step 4: TEST
Yes there was an error while making periscope, which i fixed. The position of mirror with the edge of cylinder has to be exactly 45 degree.
Step 5: Watch Detail Video on How a Periscope Works and How to Make a Periscope
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