The Electromagnetic Spectrum

[danceamber]

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Ahh colors. How fun right? .....no. lol. I mean it's cool but I always get confused. I have three main questions, if you have any insight, thoughts, or simply want to bond over how confusing light and optics can join on in! haha

1. So we know that color is essentially whatever color it does not absorb. So my shirt is red because it does not absorb red. But what about blue? I've run into a few questions where books use this interchangeably, so although a blue object does not absorb blue, does it still absorb violet? And when we talking about absorbing or reflecting colors, is this only the primary colors?

2. black versus white. I just don't understand which each reflects and absorbs

3. How does absorbing and reflecting colors relate to heat and temp? In the EK book there was a question about why astronauts where white suits instead of black, and this is completely and utterly beyond me lol

 

[BobbyKoch]

Ahh colors. How fun right? .....no. lol. I mean it's cool but I always get confused. I have three main questions, if you have any insight, thoughts, or simply want to bond over how confusing light and optics can join on in! haha

1. So we know that color is essentially whatever color it does not absorb. So my shirt is red because it does not absorb red. But what about blue? I've run into a few questions where books use this interchangeably, so although a blue object does not absorb blue, does it still absorb violet? And when we talking about absorbing or reflecting colors, is this only the primary colors?

2. black versus white. I just don't understand which each reflects and absorbs

3. How does absorbing and reflecting colors relate to heat and temp? In the EK book there was a question about why astronauts where white suits instead of black, and this is completely and utterly beyond me lol

1. Applies for all colors. So whatever color you are seeing is being reflected, including violet.

2. Black is the absorption of all colors. White is the reflection of all colors. Take a white light and shine it through a prism yielding a rainbow. (Thanks, Newton).

3. Light is energy. If your spacesuit is black it is absorbing all that light ie all that energy. Therefore you would have to work harder to cool the suit. White reflects that energy, therefore it’s easier to cool.

One thing that might help... remember that light waves are always traveling at the same speed (c or 3e8 m/s in vacuum). So what makes them different energetically? Wave length. Shorter wavelengths (blue or violet) will result in more waves “crashing” on the same location in space per unit time, more energy. Longer wavelengths like red equals fewer wavefronts “impacting” per unit time, less energy.

A question for you: using what you know about the Doppler effect as it relates to sound, what happens to the light from an object racing away from you at very high speed? Does it appear more red or more blue? What about an object racing toward you?