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CFL color Eclipse energy efficiency environment Google how-to Kill-A-Watt LED lighting science sun

How to build an eclipse viewing box with your kid

You should never look at a solar eclipse directly, but building a simple eclipse viewer is easy. It’s also a fun project to do with your kids.

Step 1. Get a long box.

Eclipse viewer box

I got a really long square box from the UPS store for ~$10. The longer the better – the more distance between the end pointed at the sun and the viewing end, the larger the image of the sun will be.

By the way, this picture is just showing off how long the box is – you won’t actually be looking through the box when we’re done.

Step 2. Decorate the box.

Decorating the eclipse viewer

This might be the most important part of the project if you’re doing it with kids. Kids love to draw planets, comets, rocket ships, and all sorts of fun things. This is also a good place to illustrate exactly what’s going on when the sun starts to disappear.

Step 3. Close the box and cut a hole in one end.

Eclipse box

This end will be pointed toward the sun.

Step 4. Cover the hole with foil and put a tiny pinprick in the middle.

eclipse viewer pinhole

You want to block out all the light except the pin prick. It will cast an image of the sun on the other end of the box.

Step 5. Cut open a small section of the side near the bottom.

Eclipse viewer ready to go

The picture illustrates this pretty well. You want a small section open so you can see the image in the bottom of the box. I also put a piece of white paper in the bottom, that shows off the image better than cardboard:

image of the sun

You’ll need to find something to use to prop up the box and aim it toward the sun. I used a tripod, but a chair will work as well. You’ll need to keep moving the viewer as the day goes on to keep the image in place.

Enjoying a solar eclipse

Caught in an eclipse without a viewer? No worries! Anything with a hole in it that can cast a shadow will show the eclipse – even your fingers or the leaves on the trees!

solar elcipse shadows

Cresent eclipse shadows

LED Bulbs vs. Compact Fluorescent: Part II

DSC_0662 I wanted to revisit an earlier post comparing LEDs, CFLs and traditional incandescent bulbs. I found two different values for the power and light output of the Lemnis Lighting Parox II bulbs, and same folks at work were wondering the same thing.

I decided to bust out my trusty Kill-A-Watt and see how much power the bulb was really drawing.

I watched the meter for a bit and it never went above 4 Watts. So that’s a bit of a bonus. Out of curiosity I decided to plug my CFLs in and see how much power they actually drew.

The 15W CFL spiked to 18W for a second but then settled in at 12W. After a while it climbed up to 13W and would have presumably stayed there. The 7W CFL globe settled at 5W. The incandescent was the odd one of the bunch, measuring 63 W instead of 60W. So when you replace those old lightbulbs, you may be saving a little more than you think.

Here’s the updated spreadsheet:

Again, the total lumen output might not be directly comparable because the LED bulbs really only emit light from a half globe, while the other bulbs cast light in almost all directions. Depending on the fixture this might make the LED seem brighter in comparison.

How do LED lightbulbs compare to CFL and incandescent?

Spectrum of an LED light bulb One of the great things about working at Google is the company’s commitment to the environment. This week for Earth Day the company gave each employee two LED light bulbs – much more efficient than regular old incandescent bulbs and better in some ways than the twisty compact fluorescent (CFL) bulbs I already have around the house.

Energy efficiency is one thing, but how do all these different lights compare visually? Three important measures to look at are the color temperature, the color rendering index (CRI), and the light output in lumens. I’ll talk a bit about both and explain a simple science demonstration you can do in your own home.

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