light

Dot Physics

Category archives for light

What the heck is this answer 3

Congratulations Fran. Not only did she answer the “What the heck is this?” correctly, she was the first commenter. Here is the original item: It is of course a gas discharge tube. You put these tubes in there (as shown above) with helium or neon or whatever in there and it excites the gas to…

Could I build a lightning detector?

A while ago, we had a ton of lightning. As a bonus, it always happened in the middle of the night. I love sleeping where it sounds like I am on the front line in WWI – no, I don’t. But, while lying awake waiting for the next BOOM I thought of something. Instead of…

Kindle vs. iPad in the Sun

There is this commercial that has been coming on lately showing some people reading the Kindle at the beach. Why is this a selling point? It has to do with the way the Kindle works compared to something like the iPad. I would take a picture, but I have neither of these devices. Instead, I…

How fast is the Beacon of Gondor?

The Lord of the Rings trilogy came on TV again recently. My wife and I can’t help but to watch this even though we have it on DVD. Anyway, I was thinking about the part where Gondor sends a signal to Rohan asking them for military aid. Since this was before the invention of email,…

How do color filters work?

So you have seen these color filters (or gels as they are also called). When you look through a red filter, everything looks red. What do they do to the light? I am not going to tell you the answer. However, I will show you some examples so that you can figure out the answer…

Hug a Laser

It is my duty as a blogger to mention lasers in this time of international laser celebration. This May is the 50th anniversary of the first lasers. Everyone knows a laser that they love, right? We all use them. So, instead of talking about lasers, I am going to post some great links to other…

Why is it dark inside?

This was a great question. When you come inside after playing in the sunny outside, why is it so dark? Simple answer: because your eyes are smart. When you are outside, there is a lot of light. Really, it is too much light. To compensate for this, your pupils (the part of your eye that…

Green Laser and Fluorescence

Do you have a green laser pointer? You should. They are relatively inexpensive now. What if you take your laser pointer and aim it at stuff in your house? The laser dot always looks green, right? This is actually a pretty important point about color. Suppose I have the lights on in a room and…

Here is a picture of something you have seen before. These are two pictures of the same location in my house. The one on the left is taken when the Sun was up outside and the other one when it was dark outside. For both pictures, I had the same lights turned on inside. So,…

When to not use a camera flash

Check out this picture. These camera flashes are just awesome (well, they look awesome). They are not a very useful thing for pictures in this case. Here is the problem. Well, first here is what the flash on a camera is supposed to do. Suppose there is a camera and a ball in a dark…