FRUIT POWER EXPERIMENT

Purpose & Background: This experiment demonstrates the conversion of chemical energy to electrical energy using acidic solutions as the generator. Voltaic batteries change chemical energy into electrical energy. Batteries are comprised of two different metals suspended in an acidic solution. The metals are electrodes, which are the parts of a battery where electrical current enters and leaves it. In this case, the two metals are zinc and copper from the nails. The acid comes from the citric acid inside the different fruits/vegetables. The flow of electrical current passes through both electrodes through the acidic solution inside the fruits/vegetables. Once the battery is connected to the LED, a complete circuit is formed. Our experiment takes this concept and adds in the element of questioning whether PH level of the solution affects electricity production. Solutions that are very acidic are high in PH level. We chose various acidic-leveled fruits/vegetables to see if this has an affect on the battery. We also chose to add in using a regular AA battery to have a constant in our experiment.   Our fruit power experiment turned out to be a success through trial and error.

Materials: 1 Double AA Battery, 2 Lemons, 2 Oranges, 2 Limes, 2 Tomatoes, 4 Paper Cups, Knife, 4 Zinc (negative) Nails, 4 Copper (positive) Nails, 1 Red LED, 4 Negative Wires (Black), 4 Positive Wires (Red), Clamps for Wires, Voltage Meter, PH Strips, Electricity Grid

The Experiment: The first part of our experiment, testing PH, worked as planned. We squeezed the juice from a lemon, orange, and tomato into the cup. Students then put PH strips into the cups and allowed them to measure the level of PH of each juice. We collectively found the juices to be acidic. The lemon had a PH of 2.5, the orange had a PH of 3.5, and the tomato had a PH of 4.5.

We decided to add a battery as a constant to the experiment since we knew it would be able to light the LED. The voltage of the battery was 1.55V and lit the LED brightly. We realized the fruit needed to be around this voltage to light the LED. We had hoped that one fruit would light one LED.  We initially planned to light the LED using each fruit and comparing this back to its voltage. The lemon had a voltage of 1.3V, the orange had a voltage of 1.1V, and the tomato had a voltage of .9 V. We found that the fruit had a voltage, however the current was not strong enough for one single fruit to light the LED on the grid.

First we tested the lemon and found it was a very dim. Next, the orange and tomato did not light the LED. We decided to try and combine the voltages of the fruit. Using clamped wires, we connected all of the fruits together and back to the grid to complete a complete circuit. This proved to be successful.

To further alter our experiment we decided to put the copper and zinc nails right into the juices of the fruits. This also was a success, even more so than the using the fruit itself. We came to the conclusion that the juice is what holds the electrochemical potential, not the whole fruit.

Results: Overall, we found that this experiment took trial and error. Though the singular fruits did not light the LED, it was not a matter of the fruit’s electrochemical potential, but actually the lack of current running through the wires. We had to combine the voltages to get the current needed to light the LED. Though juice may not be able to power your home, it was interesting to see the potential power that is in a natural resource. Perhaps through development we will be able to harness this natural resource and use it as an alternative to other environmentally dangerous uses.