NEW ZEALAND TARANAKI

A Lemon Juice Cell

Make sparkly lemonade that can also make sparks!


  • Get one lemon (or any juicy fruit or vegetable).
  • Push an iron nail into one end, and a bit of bare copper into the other end

That's it! Simple isn't it?

If a voltmeter or one of those battery testing strips is touched to each end you will see that electricity is being produced.

Even a saucer of salty water will do the same trick as a lemon...

Lets have some fun!

  • PREDICT: Ask your students "What will happen if 2 pieces of copper are used?
  • OBSERVE: Let the students determine if a voltage is produced
  • EXPLAIN: What does this show us? (seniors might like to consider the chemical reaction involved)
  • PREDICT: Ask your students "What combination of 2 different metals produces the greatest voltage?
  • OBSERVE: Let the students determine if a voltage exists
  • EXPLAIN: What does this show us? (seniors might like to consider the chemical reaction involved and the Activity Series for metals)

Try a zinc galvanised nail and an ordinary iron nail; a bronze coin and a piece of aluminium.

Cells and batteries - what's the difference?

You have just made an electrochemical cell. Electrochemical means making electricity from chemicals. Slightly acid or salty water reacts with our two different metals to produce electricity. A good cell should produce about 1.5 volts, about the same as a Duracell. We often call the electrochemical cells we buy from the shop "batteries". A true battery is more than one cell connected to others to produce a higher voltage.

A car battery is a true battery made up of 6 cells each producing 2 volts, adding up to a total of 12 volts all together. AA, C and D size Energizer brand "batteries" are single cells!

You'll notice that these Energizer and EverReady "batteries" bought from shops can contain a "paste" inside them so that liquid doesn't slosh around and leak everywhere, unlike the cell we made.

The so called "batteries" bought from the shop only make electricity for a while. When they no longer produce electricity we say they are "flat", even though they haven't changed shape at all! Confusing!

Saline Cell Toys - SCT's

A Nexus prototype cell developed by Year 10 student Jared Broad in 1999 used the idea of using two different metals inserted into salty playdough. Like an Energizer "battery", our Saline Cell did not contain any liquid to slosh and spill.

Jared could even add food colouring to make the dough "batteries" look more fun. Below are just a few examples of simple toys he developed for the 1999 Science fair (Jared was really busy that year - entering ALIS the robot, and a clever oscilloscope computer program and circuit as well!).

Electricity from salty play doh (play dough) ... a simple 'battery'

A play doh (play dough) battery is easy to make and does not spill. A saline cell toy (SCT) is shown here

The SCT power supply - two salt dough cells produce about 3 volts.

The saline cells (salty playdough) kept this toy going and going and going....

Want to make a Christmas tree with flashing lights and music?

Imagine adding a PICAXE chip...

Nowadays Jared has a degree in Biophysics and combines Computing, Electronics and Biology expertise...

Electricity from salty play doh (play dough) ... a LED is powered for many hours with no liquid to spill

FIND OUT MORE:-

  1. Which two metals produced the most volts?
  2. Build sensors to detect current, voltage, conductivity, etc, using a digital multimeter
  3. Use an salt dough cell to power your own toys and cyberpets
  4. Some electrochemical cells can be used again and recharged. Try to make your own rechargable battery...
  5. There are other ways to generate electricity. Build your own electrical generator here...
  6. Read about the New Zealand Energy Conservation and Renewable Energy Generation Pilot Project
  7. The interactive pages...identify these pieces of lab equipment
  8. The interactive pages...weird metals and gases hide in this Periodic Table
 

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