Category: sunlight

What causes a magnifying glass within a ray of sun to burn such a small, specifi…

Lou Bloomfield Leave a comment

What causes a magnifying glass within a ray of sun to burn such a small, specific spot? Is it the shape of the glass?

The magnifying glass is a lens, a carefully shaped piece of glass that can refract sunlight to create an image. When you burn wood with a magnifying glass, you are creating an image of the sun on the wood. This tiny image, a circle that looks just like the sun itself, only much smaller, is so bright and contains so much thermal radiation that it overheats the wood that it strikes and causes that wood to burn.

Why does purple bend more in a prism than, say, red?

Lou Bloomfield Leave a comment

Why does purple bend more in a prism than, say, red?

Purple (or violet) light travels slower in most materials than does red light. That occurs because violet light is higher in frequency than red light and gives the charged particles that it jiggles about less time to move up and down. With very little time to move, these charged particles barely notice that they are parts of atoms and molecules and respond easily to the passing electromagnetic wave. But when red light pushes and pulls on charged particles, there is more time for them to find the limits of their freedom. These charged particles are not able to move so easily when pushed on by a passing wave of red light so they do not interact with that passing wave as well as with one of violet light. Thus red light passes by with less effect and it behaves more like it would in empty space. Violet light, which interacts relatively strongly with the atoms it passes, slows down more than red light. Since red light travels more quickly than violet light, it bends less in passing through a prism. Violet light slows down more and bends more than red light.

What causes the colors in the aurora borealis?

Lou Bloomfield Leave a comment

What causes the colors in the aurora borealis?

These colors come from the atomic fluorescence of particles high above the earth’s surface. As charged particles from the sun’s “solar wind” spiral through the earth’s magnetic field toward its poles, they collide with one another and with atoms in the earth’s upper atmosphere. The energy of such collisions can excite the atoms involved and cause them to emit light.

Why doesn’t light go through the other side of a water droplet, refracting as it…

Lou Bloomfield Leave a comment

Why doesn’t light go through the other side of a water droplet, refracting as it goes through, rather than reflecting back?

Actually, 96% of the light hitting the “other side of a water droplet” does pass out of the droplet. What you see in the rainbow is the 4% that reflects back from the far side of the water droplet. If all of the light reflected, the rainbow would be much brighter.