Primary · P4–P6
Round 1/6Score 0

Echo and Shadow

Sound needs a medium. Light travels in straight lines.

Challenge

Live model
wavelength λCrests repeat one wavelength apart
Light makes clear or blurry shadows depending on the material.
The physics

Sound needs a medium (air, liquid or solid); it cannot travel in vacuum. Light travels in straight lines. Similar triangles: shadow height / object height = screen distance / torch distance. Simplified point torch.

Live measurements

Lab complete!