Periscope

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.

Science background:

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.