Why do shadows exist?
Show answer & explanation
Answer: Light travels in straight lines
Objects absorb all light — Wrong. Shadows aren't from light absorption. They form because light travels in straight lines—opaque objects block light, creating dark areas behind them.
Light travels in straight lines ✓ — Correct! Light travels in straight lines (rectilinear propagation). When an opaque object blocks light, it creates a shadow—a region where light can't reach because it can't bend around the object. Shadow size/shape depends on light source position and object distance. Multiple light sources create multiple shadows!
Gravity bends light downward — Wrong. Gravity doesn't significantly bend light near Earth. Shadows form because light travels straight—objects block it, creating dark regions.
Go deeper: Rectilinear propagation
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