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Physics · Optics

Build a periscope and test the law of reflection

Make a periscope from card and two mirrors and show that both must sit at 45 degrees.

  • DifficultyBeginner
  • Estimated time1–3 hours
  • BudgetUnder ₹250
  • ClassClass 6–8
  • TeamSolo or up to 2
  • You needHousehold materials

Prerequisites: None beyond your class work

Original · by TechnifyedWorking ModelBeginner friendlyLow cost

My projects

Overview

Make a periscope from card and two mirrors and show that both must sit at 45 degrees.

Skills you will use

Angle measurementCutting and assembly

Safety

  • Glassware can break. Handle it over a table, and clear up broken glass with a brush, not your hands.
  • This project uses a blade or sharp tool. Cut away from your body on a cutting mat, and ask an adult to help younger students.

Materials and tools

  • Two small plane mirrors
  • Thick card or a long box
  • Tape
  • Protractor
  • Cutter

Tools and software

Protractor

Expected costUnder ₹250About ₹80 at most, less if you borrow parts
Estimated duration1–3 hours4 build steps, plus the report

Step-by-step roadmap

  1. Start

    You will finish with: a working periscope and a ray diagram.

  2. 1

    Prerequisites

    Nothing special to know first. Then collect the 5 items in the materials list.

  3. 2

    Learn

    Read up on optics: angles, mirrors, reflection. Your textbook chapter and one short video are enough.

  4. 3

    Plan

    Sketch the design, list every part with its price and decide how you will know it works.

  5. 4

    Build

    1. Cut two windows on opposite sides at opposite ends of the box.
    2. Fix a mirror behind each window at exactly 45°.
    3. Look through the lower window and view objects over a wall.
    4. Change one mirror to 40° and note what happens to the image.
  6. 5

    Test

    Run it ten times in a row. Note every failure, fix the cause and test again.

  7. 6

    Document

    Photograph each build stage, keep the circuit or drawing, and note what failed and how you fixed it. Report structure

  8. 7

    Present

    Demonstrate it working first, then explain how it works and what you would improve. Presentation structure

  9. 8

    Publish

    Share a short video, the parts list and the drawing or code so someone else can build it.

Expected outcome

A working periscope and a ray diagram.

Other versions of this project

Advanced version

Add a third mirror to make a rear-view periscope and trace the rays.

Science fair mode

Text marked "You write this" is a prompt for your own work; everything else is specific to this project.

Problem
You write thisWrite your question as: How does [what you change] affect [what you measure]?
Hypothesis
You write thisWrite it as: If [I change this], then [this will happen], because [reason].
Variables
You write thisName the one thing you change (independent), the thing you measure (dependent) and what you keep the same (controlled).

Materials and procedure are in Materials and the Roadmap.

Observation table

You write thisDraw a table with one column for what you change, one for each repeat reading and one for the average.

Graph
You write thisPlot what you changed along the bottom and what you measured up the side; use a bar chart for categories and a line graph for numbers.
Results
You write thisState what the graph shows in one or two sentences, with numbers.
Conclusion
You write thisSay whether the result supports your hypothesis and why you think so.

Display board

  • Title and your name
  • Question
  • Hypothesis
  • Materials
  • Procedure (with photos)
  • Data table and graph
  • Conclusion
  • What you would do next

Questions judges ask

  • What would you change if you did this again?
  • What was your biggest source of error, and how did you reduce it?
  • Where is this idea used in real life?

Working as a team

Solo or up to 2. Suggested roles:

DesignHardware and buildCode or controlTestingDocumentationPresentation

Report and presentation

Report structure

  1. Title and aim
  2. The problem it solves
  3. How it works (principle)
  4. Parts list with cost
  5. Design: drawing, circuit or block diagram
  6. Build steps
  7. Testing and results
  8. Problems faced and fixes
  9. Limitations
  10. Future improvements
  11. References

Presentation structure

  1. The problem
  2. The idea
  3. How it works (one diagram)
  4. Parts and cost
  5. The build (photos)
  6. Live demo or video
  7. Test results
  8. What did not work
  9. Next version

Viva questions

Prepare your own answers to these before you present.

  • What is the aim of your project, in one sentence?
  • What is the principle behind it?
  • Why did you choose these materials or tools?
  • What result did you get, and was it what you expected?
  • What went wrong and how did you fix it?
  • How could this be improved or used in real life?

Resources

PhET interactive simulationsphet.colorado.eduNCERT textbooksncert.nic.in

Source and attribution

Original

Written by Technifyed. Free to use for your own school or college project; write the report in your own words. Added 1 Oct 2026.

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