Ages

Introduction

Summary

A light source doesn't create a shadow ! Light sources create light  !
When you commonly say that light hits an object and casts a shadow, you have to understand that light doesn't reach the area behind the opaque object - the area we call the shadow.
In fact, the brightness behind the object remains the same if you switch off the street lamp in front of it. Seeing a shadow is just a question of contrast.
If you want to build a world without any shadows, then you have two solutions:

• Switch off all light sources.
• Switch on many light sources everywhere !

Goals

• To understand that a shadow appears by contrast.
• To define Contrast and brightness.

Features

Click on the street lamps to turn them on or off.
Move the luminosity indicator (arrow) to observe contrasts.

Student sheet

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Tags

brightness luminosity light shadow contrast obscurity