Light Absorption and Reflection
Light Absorption and Reflection is how surfaces soak up or bounce back light and heat.
Two flat trays sit side by side in the sun — one painted black, one painted white. The black tray soaks up most of the light that hits it, so it gets very hot. The white tray bounces most of the light back, so it stays cool. Dark things soak up more light and turn it into heat; light things bounce it away.
Explaining light absorption and reflection by grade level
A black bottle in the sun gets very hot. A white bottle stays cool. Dark colors soak up the light. Light colors bounce it away.
Projects that explore light absorption and reflection
Dark colors absorb sunlight while light colors reflect it — and you can see this difference in real time. You paint one bottle black and one white, stretch a small balloon over the mouth of each, and place both in bright sunlight. Within minutes the balloon on the black bottle begins to inflate as the absorbed energy warms the air inside, while the white bottle's balloon stays flat.
Shiny surfaces reflect light rather than absorbing it, and that property makes them useful for directing sunlight. A parabolic curve lined with aluminum foil, shiny side out, bounces light toward a single focal point. All that reflected light concentrates at one spot instead of being soaked up by the surface.
When you angle a flat mirror or a parabolic dish toward a solar cell, reflected sunlight hits the panel in addition to direct sunlight, increasing the light the cell absorbs. The parabolic dish, covered with aluminum foil, reflects and concentrates more of those rays onto the absorbing surface than a flat mirror can. That difference in concentration is why the parabolic reflector produces the highest power output, followed by the flat mirror.
Sunlight changes things it hits. Paper left in the sun fades. Leaves block the light. The covered spots stay dark.