sweet sugar
Why Do Citrus Fruits Conduct Electricity?

Citrus fruits and many other fruits and vegetables, like apples and potatoes are good conductors of electricity. You can even use fruit juices and vinegar as a viable conductor for electricity. Many small household items can be powered using citrus fruits. Hand-held pen bulbs, LED's that use less electricity than the usual light bulbs, and even calculators can be powered using citrus fruits.
Citrus Fruits Complete the Circuit
┗ Acids when dissolved in water are good conductors of electricity and, when connected to a circuit, become electrolytes. If the same acid was used in an anhydrous form (dry/powder/crystalline form), it wouldn't have conducted any electricity. Therefore it can be concluded that water is the 'conductor' and acid is the 'producer' of electrons.

┗ When copper comes in contact with air, it forms a black-colored copper oxide film on its surface. When you pierce the copper nail in the lemon, the hydrogen atoms from the acid start reacting with the oxygen in the oxide to form water. This leaves the positively charged copper ions, Cu2+ free.

┗ Zinc metal's rate of reaction with acid is higher than that of copper. It dissolves in the acid to form Zn2+ ions and 2 free electrons. These 2 electrons rush towards the positively charged copper ions and neutralizes them.

┗ This whole process releases energy. For every 1 coulomb of charge moved, 1 Joule of energy is released. Therefore it can be said that the battery produces 1 Volt of current.

┗ A limitation to the flow of charge is the design of the interior of the fruit, it hinders the movement of ions. Another limitation is that after a certain extent, as zinc keeps on giving out electrons, it develops more positive charge and copper keeps on accepting electrons and become negatively charged.

┗ This reduces the difference in voltage between the two and the output of current reduces. But if you wait for a while, the ions redistribute themselves again and the voltage starts increasing.

┗ It should not be misunderstood that citrus fruits create electricity, they do not. They just conduct electricity by helping in completing the circuit.

┗ One or two fruits in a circuit, will generate a very weak current. But if you join a few of them in a series, in the circuit, you will be able to produce enough electricity that can light up a bulb. This kind of setup will be like a multi-cell battery.