Wednesday, November 26, 2014

Mirrors and Reflection; Make a periscope; Make a one-way mirror

There is so much to learn about mirrors and reflection! We really liked making this periscope for an activity. (You can find instructions for a similar periscope here.) We wished it could have been even longer, but longer periscopes make the image you see even smaller, so maybe it wouldn't have been as cool as we thought.
More resources on reflection: 

Video about How mirrors are made

Another (sort of silly) video on how mirrors work

(As I mention on the telescope post, the videos here on how liquid mercury mirrors are made are very interesting also.)

This page talks about different types of reflection (specular vs diffuse)

This page is great—lots of good diagrams, explanation of what is happening in convex vs. concave mirrors, why mirrors reverse what we see, etc.

The children were always asking about how the auto-dimming rearview mirror in our car worked, and I had wondered a lot about it myself! We found a couple sites that explain it well: here and here.

We also talked about one-way (or is it two-way?) mirrors. The kind that look like a mirror on one side, but you can see through them like glass on the other side. :) 

This site gives a good explanation of how they work, as does this one. The basic idea is that you need a very, very thin film of reflective material—so thin that with a strong light on one side, you can see through it, but without that back light, it reflects light like a mirror would.
Knowing this, you can make your own fairly easily. We got it to work, though not perfectly. We took a clear piece of glass from a picture frame and covered it with thin Mylar sheets (something like this) on one side. It worked just like a mirror when the lighting on both sides of it was consistent. Thus you can see me in the mirror, taking a picture with the camera. (left side, above)

However, when we dimmed the lights on one side, and turned on a bright lamp on the other side, the "mirror" became more of a "window," and I could see Abraham looking at me through it (right side, above).

No comments:

Post a Comment

Related Posts Plugin for WordPress, Blogger...