LITTLE QUESTIONS / LIGHT & SHADOW
Same little ball.
A bigger shadow?
A light, a ball, a wall. Let’s see what happens.
A shadow forms where an object blocks light from reaching a surface. With a nearby light, moving the light closer to the object makes its shadow larger; moving the object towards the wall makes its shadow smaller.
The 3D view could not load. The wall view and controls still show the calculated shadow.
LIGHTBALLWALLThe golden lines show light just grazing the ball. The shadow lies between them.
The ball and wall stay still. Only the light moves.
Read the science behind this exploration
Why does a shadow change size?
A shadow forms where an object blocks light from reaching a surface. With a nearby light, moving the light closer to the object makes its shadow larger; moving the object towards the wall makes its shadow smaller.
- A shadow is blocked light
- An opaque object blocks direct light. A surface behind it receives less light and shows a shadow. The object is between the light source and the surface.
- Distances change the shadow
- In this experiment, light spreads from a point source. Bringing that source closer to a fixed ball makes the ball block a wider cone of rays, enlarging the shadow on the wall. Moving the ball towards the wall while the light stays fixed makes the shadow smaller.
- Real lights can make softer edges
- An ideal point light produces a sharp shadow. Real torches have a finite light-emitting area and may produce a partly shaded edge called a penumbra. The golden guide lines in this lesson are a diagram aid, not light normally visible in clean air.
THE LITTLE “AHA!”
Light travels straight.
The ball gets in its way.
A shadow is where the ball blocks light from reaching the wall. The ball stays the same size, but its shadow can change.
Bring the light closer to the ball: its shadow grows. Move the ball towards the wall: its shadow shrinks.
Remember Earth? Night is sunlight blocked by Earth. ↗