Light travels in straight lines in this model. The rays passing the object’s top and bottom set the shadow’s edges on the screen. Near the lamp, the object blocks a wider spreading bundle before it reaches the screen. Near the screen, its shadow is closer to its own size. Compare the two positions while keeping the object’s height fixed.
Light, sound and electricity · Discover & try
What makes a shadow bigger?
Reading level 2 of 5 · DevelopingChange
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opaque
Not letting the model light pass through.
ray
A line representing the direction light travels.
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See how it works
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Point-source projection; sharp edges and distances are idealised, not a real lamp measurement.
What to look for
- Edge rays continue straight
- The object keeps its own size
- A closer object makes a wider projection
Explain what you noticed
A fixed screen is 6 units from a point lamp. A 1-unit object moves from 3 units to 2 units from the lamp. What happens?
Keep this idea: A shadow can change size without its object changing size.
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Source material checked 2026-10-29. Explanations and activities by Nepedia. Source links do not imply endorsement.
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