Mysteries of the Power!

By Ava Haque 4th Grade class of Mrs. Herr

1 Introduction

Did you know that the lemon can generate power? The lemon battery has the same structure and operation as a normal battery. The way this works is that, both Regular Battery Lemon Battery and react with the citric acid, our . This makes zinc, copper and electrons. e‐ e‐ e‐ e‐ But zinc is more active than copper, e‐ e‐ e‐ e‐ e‐ so it has more electrons. This makes e‐ e‐ e‐ the zinc negative and copper positive. This makes the electrons flow from

www.brighthubengineering.com the zinc to the copper.

2 Hypotheses

These are the things that I will test:

1. Is a fresh lemon a better battery than an aged lemon?

2. Will more area produce more power?

3. Does power depend on electrode distance?

3 Needed Materials

We need (1) , fresh and aged (2) zinc coated metal wire (3) a copper penny.

Lemon

Multi meter

For hypothesis # 2, we need two zinc wires with different surface area

4 Hypothesis 1

Is a fresh lemon a better battery than an aged lemon?

Dirty electrode To test this hypothesis, we did a very long 0.14 experiment. We found that the output 0.12 0.1 power decreases as the lemon ages. Watts) ‐ 0.08 0.06 (milli Two things happen (1) the electrolyte ages 0.04 and produces fewer electrons (2) the 0.02

react with electrolyte to make Power 0 dirty black stuff. 0 5000 10000 Time (minutes) Together, they decrease the power

5 Hypothesis 2

Will more electrode area produce more power?

To test this hypothesis, we did two experiments = 0.96 V, Current = 0.18 milli – amp with the same anode and two different cathodes. These two cathodes are the same material and volume.

The multithreaded wire has more surface area. More surface area means more electrons. More electrons means more power. So, even though they are same material and volume, the Voltage = 0.90 V, Current = 0.15 milli – amp multithreaded wire produces more power.

6 Hypothesis 3

Does power depend on electrode distance?

1.4 1.2 1 Voltage (V) Current

0.8 0.6 and 0.4 0.2 Current (m‐A) 0 Voltage 02468 Distance (cm)

Current decreases as we increase the electrode distance

7 Hypothesis 3 (continued)

We saw that voltage stays the same while current decreases. WHY??

A battery is not just plus and minus terminals. Between the plus and minus terminals, we have an electrolyte. This electrolyte gives internal resistance to the battery.

When the electrodes are a further Electrolyte resistance distance, the resistance is higher. When the resistance is high, the current is low.

8 Conclusions

I conclude that the power of the lemon battery is not constant. The power depends on the age of the lemon (acidity of electrolyte), the electrode surface area (how many electrons produced), material type (ability Dreamstime.com to produce electrons), and the resistance to the flow of electrons by the electrolyte itself.

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