BATTERY BASICS The Lemon Cell (Battery)

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BATTERY BASICSThe Lemon Cell (Battery)

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BATTERY BASICS INTRODUCTION

• 1800 Alessandro Volta discovered the chemical
  battery by creating a portable electricity source
  known as a Voltaic Pile.
• A Voltaic Pile is a device using pieces of silver
  and zinc separated by moist cloth soaked in an
  electrolyte (in Voltas case, sea water)
  solution.
• Humphry Davy later proved that the electricity
  from voltaic piles was caused by the chemical
  reaction, and not the different metals, as first
  assumed.

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BATTERY BASICS Voltaic Pile

• In the lemon experiment, the lemon juice allows
  the metal plates to gain or lose electrons. Then,
  those electrons travel over to the other plate
  (via the electrolyte solution, lemon juice),
  forming a redox reaction.
• The electrolyte is electrically the same on both
  sides, but the reaction creates a different
  electrical potential on the two different plates,
  so connecting them shows a voltage difference.

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The Lemon BatteryMaterial List

• Figure 1 Alligator clips with wires attached.
• Figure 2 Copper and Zinc metal strips
  (Galvanized Sheet Steel will work fine for the
  Zinc strips)

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The Lemon Cell (Battery) Material List

• Figure 3 A sharp knife and extra fine steel wool
  or Scotts Brite
• Figure 4Galvanometer

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The Lemon Cell (Battery) Material List

• Figure 5 Multi-Meter
• Figure 6 LEDs (1.8 volt)

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The Lemon Cell (Battery)Material List

• Figure 7 Thermometer with LCD Digital Display
• Figure 8 DC Motors and computer fans.

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The Lemon Cell (Battery)Material List

• Figure 9 Lemons
• Figure 10 Egg Crate to hold lemons

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The Lemon Cell (Battery)Assembly Procedures

• Step 1 Obtain a Copper and Zinc Strip and clean
  both sides with steel wool or Scotts Brite
• Step 2 Obtain a Lemon, and roll it on the bench
  top to break internal fibers in the Lemon.

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The Lemon Cell (Battery)Assembly Procedures

• Step 3 Using a sharp knife, make two slits on
  one end of the lemon, as shown.
• Be careful not to cut yourself!
• Step 4 Insert a copper strip into one of the
  slits and a zinc strip into the other, as shown.
  Use an egg crate to hold the lemons.

SAFETY
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The Lemon Cell (Battery)Experiment Procedures

• Step 1 Connect the alligator clips with wires to
  the metal strips, as shown.
• Step 2 Connect the wires to the galvanometer on
  the Go terminal. Note that the needle is pegged.

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The Lemon Cell (Battery)Experiment Procedures

• Step 3 Connect the lemon to the G1 terminal of
  the galvanometer. The G1 terminal has a resistor
  inline. What happened? Why?
• Step 4 Now connect the lemon to the multi-meter
  with the range set at DCV 2. How much voltage is
  the lemon cell producing?

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The Lemon Cell (Battery)Experiment Procedures

• Step 5 Put 3 lemon cells in series. Why in
  series? Note copper is connected to zinc. Why?
  Connect as shown. Now we have a lemon battery.
  Why?
• Step 6 Connect this Lemon battery to the
  multi-meter that is set to DCV 20. Why DCV 20 and
  not DCV2? How much voltage is the battery
  producing?

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The Lemon Cell (Battery)1.8 Volt LED Lemon
Powered

• Figure 1 LED Off
• Figure 2 LED On. Using 5 Lemons. What is the
  voltage of the Lemons? What is the amperage of
  the 5 Lemons? What is the minimum number of
  Lemons that will Power the LED? What is the
  voltage of the minimum number? What is the
  amperage?

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The Lemon Cell (Battery)Powers 3Volt Digital
Electric Thermometer

• Figure 1 Thermometer unplugged. What is the
  voltage of the 4 lemons? What is the amperage?
• Figure 2 Thermometer on. What is the minimum
  number of lemons needed to power the thermometer?
  What is the voltage and amperage of this minimum
  number?

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The Lemon Cell (Battery)Can the Lemons power a
computer fan?

• How many lemons will be needed to power a 12 VDC
  computer fan? Will this be possible?