Bonus Alternative Energy Projects!

Thanks so much for joining me for the teleclass! On this page you'll find the videos for the robots that we covered in class, plus a few extras. Enjoy!

science-experimentClick here to get the new Renewable & Alternative Energy program!

Make your kids' year great and get access to hundreds of hands-on, fun science activities!

Solar Marshmallow Roaster

Materials:

  • 7×10” page magnifier (Fresnel lens)
  • cardboard box, about a 10” cube
  • aluminum foil
  • hot glue, razor, scissors, tape
  • wooden skewers (BBQ-style)
  • chocolate, marshmallows, & graham crackers

Do you like marshmallows cooked over a campfire? What if you don’t have a campfire, though? We’ll solve that problem by building our own food roaster – you can roast hot dogs, marshmallows, anything you want. And it’s battery-free, as this device is powered by the sun.

NOTE: This roaster is powerful enough to start fires! Use with adult supervision and a fire extinguisher handy.

Easy Photoelectric Effect Experiment

The photoelectric effect is used by all sorts of things today, including solar cells, electronic components, older types of television screens, video camera detectors, and night-vision goggles.

This photoelectric effect also causes the outer shell of orbiting spacecraft to develop an electric charge, which can wreck havoc on its internal computer systems.

A surprising find was back in the 1960s, when scientists discovered that moon dust levitated through the photoelectric effect. Sunlight hit the lunar dust, which became (slightly) electrically charged, and the dust would then lift up off the surface in thin, thread-like fountains of particles up ž of a mile high.

Materials:

  • soda or steel can
  • paper clip
  • sand paper
  • tinsel (or aluminum foil and scissors)
  • tape
  • foam cup
  • PVC pipe (any size)
  • brown paper bag
  • UV shortwave lamp (sometimes called a “germ-free portable lamp”)

Solar Cookies

Can you use the power of the sun without using solar cells? You bet! We’re going to focus the incoming light down into a heat-absorbing box that will actually cook your food for you.

Sunlight at the Earth’s surface is mostly in the visible and near-infrared (IR) part of the spectrum, with a small part in the near-ultraviolet (UV). The UV light has more energy than the IR, although it’s the IR that you feel as heat.

We’re going to use both to bake cookies in our homemade solar oven. There are two different designs – one uses a pizza box and the other is more like a light funnel. Which one works best for you?

Materials:

  • two large sheets of poster board (black is best)
  • aluminum foil
  • plastic wrap
  • black construction paper
  • cardboard box
  • pizza box (clean!)
  • tape & scissors
  • reusable plastic baggies
  • cookie dough (your favorite)

Solar Battery

This is the kind of energy most people think of when you mention ‘alternative energy’, and for good reason! Without the sun, none of anything you see around you could be here. Plants have known forever how to take the energy and turn it into usable stuff… so why can’t we?

The truth is that we can. While normally it takes factories the size of a city block to make a silicon solar cell, we’ll be making a copper solar cell after a quick trip to the hardware store. We’re going to modify the copper into a form that will allow it to react with sunlight the same way silicon does. The image shown here is the type of copper we’re going to make on the stovetop.

This solar cell is a real battery, and you’ll find that even in a dark room, you’ll be able to measure a tiny amount of current. However, even in bright sunlight, you’d need 80 million of these to light a regular incandescent bulb.

Materials:

  • ½ sq. foot of copper flashing sheet (check the scrap bin at a hardware store)
  • alligator clip leads
  • multimeter
  • electric stove (not gas)
  • large plastic 2L soda bottle
  • Âź cup salt
  • sandpaper & sheet metal shears

Semiconductors are the secret to making solar cells. A semiconductor is a material that is part conductor, part insulator, meaning that electricity can flow freely and not, depending on how you structure it. There are lots of different kinds of semiconductors, including copper and silicon.

In semiconductors, there’s a gap (called the bandgap) that’s like a giant chasm between the free electrons (electrons knocked out of its shell) and bound electrons (electrons attached to an atom). Electrons can be either free or attached, but it costs a certain amount of energy to go either way (like a toll both).

When sunlight hits the semiconductor material in the solar cell, some of the electrons get enough energy to jump the gap and get knocked out of their shell to become free electrons. The free electrons zip through the material and create a low of electrons. When the sun goes down, there’s no source of energy for electrons to get knocked out of orbit, so they stay put until sunrise.

For more experiments, check out my Alternative Energy Lab! 

science-experimentClick here to get the new Renewable & Alternative Energy program!

Make your kids' year great and get access to hundreds of hands-on, fun science activities!