light

Dot Physics

Category archives for light

This is one of my favorite demos. I like it because anyone can do it at home and people usually find the results surprising. Here is the situation: How much of yourself could you see in a small mirror? What if you move farther away from the mirror, can you see more of yourself? If…

Spectroscopy and Collimated light

There was a question from Jerry in a previous post: “A simple question for which I can’t find an answer: Why do you have to collimate light spectroscopy? What would happen if you didn’t collimate it?” The basic idea of spectroscopy is to look at the different colors of light coming from some source. Typically…

A small version of the seasons

So, it snowed here (in Louisiana). Sure, it wasn’t a lot, but it was still a big deal. The following day, there was still some snow on the house roofs. I took some pictures. Here is a shot looking at the North side of a house. And here is a view of the South side…

Retroflectors

One of the roads near my house was just redone. They added some awesome retroreflectors in the middle. Here is a shot. No wait, I don’t have a picture of that. I tried to take one, but it just didn’t turn out very well. Oh, you know what it is supposed to look like. It…

Parallax, what is it good for?

Very simply, parallax is an apparent motion of an object due to a change in observation position. Let me start with an example. Here are two photos. I took a picture of the cabinet in the background from two slightly different positions. In the foreground is a clone trooper that did not actually move. I…

Light and Waves – at a basic level

Yes, this can be very complicated. But what should a middle-school student understand about light? You see stuff in textbooks that is either wrong or just a bunch of disconnected factoids (I like the word factoid). So, what do I think is important about light (not at the Maxwell’s equations level) What is a wave…

Seasons, short and simple

I love this question: Why is it warmer in the summer than in the winter (for the Northern hemisphere)? Go ahead and ask your friends. I suppose they will give one of the following likely answers: The tilt of the Earth The tilt of the Earth makes us closer to the Sun We are closer…

ROYGBIV and Newton

This comes up everytime I teach physics for elementary education majors. The curriculum I use (Physics for Everyday Thinking – which is awesome) says that the colors in white light are ROYGBV (Red-Orange-Yellow-Green-Blue-Violet). Typically, I will get a student that says “Hey! What about indigo? Shouldn’t it be ROYGBIV?” My first reaction to this was…

A demo for the color black

What do you see when you are in a completely dark room with no lights? That is a great question to ask. It can bring out some interesting ideas. Anyway, here is an easy demo to show the color black. The basic idea is to build a box that has a small opening. Here is…

Another electric motorcycle post. (Here is the post on the wind-recharged drag racing motorcycle) This new one is a solar powered motorcycle. The site claims that the bike can go 50 miles on a full charge (from Gas2.org). This is easily possible, but how long would it take to charge with normal solar panels? Here…