Tuesday, February 2, 2016

My 9 year old daughter has a "bid dream" - she wants to invent a "machine" that would produce clean energy from trash. While this plan is a bit far-fetched, I thought it would be fun to make the concept of electrical energy a bit more tangible to her with a classic project for beginner makers - a lemon battery.
Electricity STEM Challenge - Make a Lemon Battery

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Supplies Needed

Activity #1: Electricity With a Lemon Battery

Smarty is not a complete newbie when it comes to electricity. Her father runs a Tinkerlab in her school and so far every fourth grader made two projects involving a battery - a jitter bug and an LED ornament. I thought that a classic lemon battery experiment will be great to help her visualize "the inside life" of a battery. She already had an understanding that electricity can be measured, and her Dad showed her how to turn the multimeter on and set it to measure voltage. Then she connected one alligator clip to a penny and inserted it into a lemon. 
Her first test was to try different materials for one of the electrodes to see which materials will produce most electricity. My husband and I expected galvanized nails to work best, she predicted a silver coin. To our surprise, paper clip end of circuit produced most electricity (about 1V). 

How Does Lemon Battery Work?

I really cannot explain it better than this video does. I love the beginning, Electricity is not in a lemon! Yep, Smarty thought it was :)

Activity #2: Light a LED with Lemons

Alas, one lemon cell battery does not produce nearly enough voltage to light even a low voltage LED. We connected three lemon cells to power one low-voltage LED light that requires about 2V. So much for powering our house with lemons and spare change! Smarty was really surprised to pull a paper clip out and see it "rusted". The chemical reaction with lemon juice oxidizes metal and creates a "rusty" residue on it. On the other hand, our pennies got much cleaner - courtesy of lemon acid bath. But cleaning pennies is a tale from another experiment.

Your Turn 

Have you tried any experiments with kids involving electricity?

More Electricity for Kids:

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28 Days of STEM

We are participating in the 28 Days of Hands-On STEM activities for kids! Check out it’s homepage to see a list of all the great STEM activities you can look forward to this month. I can't wait to see what my blogger friend offer for Green Stem, a topic of this week!

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Unknown said...

Oh, this is so cool! My 13 year old is going to love it!

Ticia said...

I'll have to show my boys this one. They'd love it.

JL said...

You are so good at finding science tools!

Theresa A said...

I have been wanting to try this experiment for a while. It seems that it would take quite a bit of power to light something with higher voltage. We will have to try this some day. Thanks for sharing what works best!

maryanne @ mama smiles said...

What a great experiment!