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LessonGrades 3 - 5

Pictures Please – Traveling Light

A pen and ink drawing shows a man drawing an image as it appears in a mirror on the top of the camera obscura. The camera is a large box on a table. Light (thus, an image) enters through a hole, is reflected off a mirror and the image is reflected onto another mirror on the top of the box.Figure 1. A camera obscura, also known as a pinhole camera, circa 1855.

Students learn that light travels in a straight line from a light source and that ray diagrams help us understand how images will be created by a lens. This prepares students for the associated activity, in which they explore the concepts behind the workings of a pinhole camera.

Optical engineers design equipment to focus and control light for a variety of purposes — for uses in medical equipment, armed forces and recreation, among many others. Optical engineers design telescopes, binoculars and even the focusing lens on CD drives.

After this lesson, students should be able to:

  • Explain that light travels in a straight line.
  • Draw a simple ray diagram.

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