Science concept behind the experiment:
Batteries are comprised of two different metals suspended in an acidic solution. For the lemon battery, the two metals, copper and zinc, are suspended in the citric acid inside the lemons.
The two metals are electrodes, the parts of a battery where an electrical current enters and leaves the battery. Electrons flow out of the copper pennies and into the zinc nail through the acidic juice inside the lemon. Once the lemon battery is connected to the LED, a closed circuit is formed and an electric current flows through the closed circuit to light up the LED.
