MAKING A BATTERY by Pie-Chart, Derek, Habib


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Materials Needed (and Why)

  • galvanized nail (zinc for the negative terminal)
  • salt (make a dissolved electrolyte)
  • piece of towel (to hold the electrolyte between the copper and the zinc)
  • copper foil (copper for the positive terminal)
  • alligator clips (to connect the terminals)
  • bowl (for saltwater)
  • water (to dissolve the salt)
  • voltmeter or LED (to test the batteries)

Alternative Materials:
  • alligator clips can be replaced with 1.5mm or other electrical wire for the middle, using safety pins, paper-clips or drying clips for the teeth

Procedure

  1. Prepare the saltwater solution inside the bowl:
    1. Fill the bowl with water
    2. Add some salt
    3. Stir
    4. Repeat 3 and 4 until there is salt on the bottom of the bowl, which means the salt is totally saturated.
  2. Prepare the towel:
    1. Cut the towel to 7cm long (depending on the length of the nail) and about 4-5 cm wide.
    2. Soak the piece of towel with the solution.
    3. Squeeze the piece of towel a little, so it does not drip.
  3. Wrap the squeezed towel over the galvanized nail, between the head and the point.
  4. Cut the copper foil to the same size as the towel.
  5. Wrap the copper foil over the nail and towel.
  6. Connecting the alligator clips to a single battery
    1. Choose two alligator clips (or 2 wires and 4 other clips).
    2. Connect one alligator clip to the copper foil.
    3. Connect the other alligator clip to the nail (the head is a good fit).

Now you have made a battery!

Testing

We are going to find which is the positive and the negative terminal of the battery, and confirm that they work.
  1. With a voltmeter:
    1. Select a voltage range of millivolts (mV) and direct current (DC, or V with a straight line over it).
    2. Hook the positive terminal of the voltmeter (red cable) to one of the terminals of the battery, or to one of the alligator clips.
    3. Hook the negative terminal (black cable) to the other terminal of the battery, or the other alligator clip.
    4. Read the voltage. If it is more than 1.5 volts it will light up an LED. A single battery will be less than 1.5 volts, but more then 0.5 volts (500 millivolts).
      1. What voltages do you get from your battery?
    5. If you do not get a reading, or if the voltage is negative, touch the black cable of the voltmeter to the other clip or battery terminal, and likewise for the red cable.
    6. If you have a positive reading, you can discover which battery terminal is positive and which is negative:
      1. Conventional current flows from the positive terminal to the negative terminal.
      2. If the positive cable of the voltmeter is connected to the positive terminal of the battery, and the negative cable to the negative terminal, do you think the voltage will be positive or negative?
  2. With an LED:
    1. The negative terminal of an LED has a shorter leg. The bottom plastic of an LED is flattened near the positive terminal and leg.
    2. If the positive and negative terminals of the LED are connected to the positive and negative terminals of a battery which has at least 1.5 volts, the LED will light up.
    3. To get 1.5 volts from your batteries, you need to make more batteries and attach them in series (negative-to-positive/positive-to-negative) to increase the voltage:
      1. Make another battery with the same procedure.
      2. Connect the copper of your first battery to the nail of your second.
      3. Connect the LED to the nail of your first battery and the copper of your second, so the wire makes a circle (or 'circuit') between battery 1, battery 2, the LED, back to battery 1, and so on.
      4. If the LED does not light, try switching the positive and negative legs of the LED.
      5. If the LED still does not light, disconnect battery 1 from battery 2. Make a third battery and connect its copper to the nail of battery 2, and its nail to the copper of battery 1.
      6. If the LED still does not light, try switching the positive and negative legs of the LED.

Once your LED has lit, answer this: which is the positive terminal of the battery? Which is the negative?



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