The fruits will produce electricity due to the acidity contained inside which causes a chemical reaction that breaks down the metals into ions. However, I don't think they will be a reliable energy source because they have limited shelf-life.

Electricity is the movement of electrons. An electron is a subatomic particle that is found in all atoms. When electrons move in a specific direction, they create an electric current. An electric current is the flow of electric charges through a conductive material. When an electric charge like an electron flows through a conductive material, it creates electricity. We use electricity in our everyday lives for many different purposes and we shouldn't take it for granted. Making a battery with a fruit works similarly to a normal battery. A battery consists of three parts, the anode, cathode, and electrolyte. In a regular battery, the cathode is the negative side and the anode is the positive side. In a fruit battery, the copper is the anode and the zinc is the cathode. The inside of a battery contains electrolytes and these electrolytes transfer ions back and forth. 

Part 1: Create Lemon Battery Contraption (Voltaic Cell):
Variables 

Control: Battery Setup |  Manipulated: Cell Type  | Responding: Voltage

Part 2: Testing Different Parts of Lemon

Variables  

Control: Battery |  Manipulated: Lemon Part | Responding: Voltage

Part 3: Testing Lemon Battery Reliability. 

Variables 

Control: Battery |  Manipulated: Time   | Responding: Voltage

art 1: Create Lemon Battery Contraption (Voltaic Cell):
Variables 

Control: Battery Setup |  Manipulated: Cell Type  | Responding: Voltage

1. Take the lemon, inserting the copper stick into one side, and the zinc nail onto the other as pictured by the diagram (See Figure.1) Ensure the two metals are not close to each other inside. This is because if they are too close then the electrons will flow through the metals instead of the wires.
2.  Use one copper wire and wrap one of its ends around the copper stick, leaving the other end free. Do the same with another wire but instead with the zinc nail. See Figure.1 for more specifications.
3. Use the Multimeter to measure the voltage generated by the lemon from the edges of the contraption, The very end copper and the very end zinc. Record observed voltage.
4. Repeat Steps 1 and 2, and connect the lemons in series to each other using a copper wire to connect them. Ensure it is connected copper → zinc → copper, etc. (See Image.1). Repeat Step 3 until voltage is enough for the LED. 
5. Record the voltage and the number of lemons needed to achieve it.
6. Wrap the free ends of the copper wires from the edge of the battery to each end of the LED. Record LED Brightness as a Qualitative observation.
7. Repeat Step 6, replacing the Lemon Contraption with a AA Battery. Record LED Brightness as a Qualitative observation.

Part 2: Testing Different Parts of Lemon

Variables  

Control: Battery |  Manipulated: Lemon Part | Responding: Voltage

1. Repeat Part 1 of the Experiment, instead replacing the Whole Lemon with Just Lemon Skin. Record Respective Observations.
2. Repeat Step 1 with Pure Lemon Juice, Record Observations.

art 3: Testing Lemon Battery Reliability. 

Variables 

Control: Battery |  Manipulated: Time   | Responding: Voltage

1. Use Same Lemon Battery & AA Battery Apparatus in Part 1. Ensure the circuit for each is complete.
2. Measure and record the voltage obtained from both contraptions.
3. Leave the battery's continuously running, recording the voltage and brightness every 1 hour.
4. Continue until it stops working.

Observations and Findings:

1. Voltage per Lemon: On average, 1 lemon produces 0.383 volts.
2. Lemon Circuit:
   • It required 7 lemons in a circuit to light an LED, producing a very dim light.
3. AA Battery Circuit:
   • 2 AA batteries were sufficient to light the LED brightly.
   • Both setups produced comparable voltages, but the AA batteries were more effective for brightness.
4. Lemon Battery Duration:
   • A lemon battery in a circuit lasted 6 hours before completely stopping voltage production.
5. Voltage Trends:
   • While adding more lemons increased the collective voltage, the average voltage per lemon decreased.

By testing if lemon juice and a lemon rind had voltage I was able to prove my hypothesis right because it was indeed the acid in the lemon that caused a chemical reaction that breaks down the metals into ions. In my hypothesis I also said That i thought it wouldn't be a reliable energy source due to shelf life and I proved that half right because the lemon stopped producing electricity after 6 hours but not because of their shelf life. The experiment also answered my question because it showed exactly how the electrons flow through the wire and how the acid breaks down the metals into ions. I was able to answer all the questions I had and learned a lot of new knowledge by doing experiments.

This experiment will apply in the real world because I can use the concept of fruits producing electricity for something else. For example, I can use different acids and metals to create a new type of battery that is biodegradable and more efficient. This is crucial because regular batterys aren't good for the enviroment and dont last long which is there main weakness.

When I did part 3 the voltage of the lemon was going up instead of down which was surprising. I then realized that I had forgotten to complete the circuit and when I did it started to go down.  When I first got my multimeter it wouldn't read the voltage of 1 lemon. I was confused for the whole day until I read the instructions and it said the minimum voltage reading was 8. Once I put 2 lemons together it started working.

How to Make a Lemon Battery

https://www.youtube.com/watch?v=GhbuhT1GDpI

What is Electricity? - SparkFun Learn

https://learn.sparkfun.com/tutorials/what-is-electricity/all

What is a Battery?

https://www.youtube.com/watch?v=-EB7NVA7rI4

I  thank my Dad for helping me with ideas, my brother for helping me with formatting, and my sister for her support and for being a good role model.