technifyed
Weekly list
Opportunities
Learn
ProjectsInterview prepAI toolsGet the weekly list

Popular: InternshipsScholarshipsFree coursesInterview prep

Chemistry · Electrochemistry

Build a lemon battery and compare fruits

Make cells from fruit, zinc and copper, measure their voltage and light an LED with several in series.

  • DifficultyEasy
  • Estimated time1–3 hours
  • BudgetUnder ₹250
  • ClassClass 7–10
  • TeamSolo or up to 2
  • You needHousehold materials

Prerequisites: None beyond your class work

Original · by TechnifyedExperimentWorking ModelBeginner friendlyLow costWell documented

My projects

Overview

Make cells from fruit, zinc and copper, measure their voltage and light an LED with several in series.

Why build this?

It makes the idea of an electrochemical cell visible with things from the kitchen.

What you will learn

  • How two different metals in an electrolyte make a voltage
  • Why cells are joined in series
  • Why voltage and current are different things

Skills you will use

Measuring voltageSeries connection

Safety

  • This project uses a blade or sharp tool. Cut away from your body on a cutting mat, and ask an adult to help younger students.

Materials and tools

  • Four lemons and two other fruits or vegetables
  • Galvanised (zinc) nails
  • Copper wire or coins
  • Crocodile leads
  • Multimeter
  • Red LED

Tools and software

Multimeter

Expected costUnder ₹250About ₹150 at most, less if you borrow parts
Estimated duration1–3 hours5 build steps, plus the report

Step-by-step roadmap

  1. Start

    You will finish with: a table of voltages for each fruit and a series battery that lights an LED.

  2. 1

    Prerequisites

    Nothing special to know first. Then collect the 6 items in the materials list.

  3. 2

    Learn

    • How two different metals in an electrolyte make a voltage
    • Why cells are joined in series
    • Why voltage and current are different things
  4. 3

    Plan

    Write your question, your hypothesis and the one thing you will change. Draw the table you will fill in before you start.

  5. 4

    Build

    1. Push a zinc nail and a piece of copper into a lemon, 2 cm apart.
    2. Measure the voltage across the two metals.
    3. Repeat with a potato, an orange and a tomato.
    4. Connect four lemon cells in series and measure the total.
    5. Connect the LED the right way round and see if it lights.
  6. 5

    Test

    Repeat every reading at least three times and check the result against what the science predicts.

  7. 6

    Document

    Record every reading with its unit, photograph the setup and draw a graph of the result. Report structure

  8. 7

    Present

    Explain the question, the method and the graph in two minutes; keep the setup ready to demonstrate. Presentation structure · Viva questions

  9. 8

    Publish

    Share the report and photos with your class, a science fair or your school magazine.

Expected outcome

A table of voltages for each fruit and a series battery that lights an LED.

Other versions of this project

Beginner version

Measure the voltage of one lemon cell.

Advanced version

Measure current as well, and explain why the voltage is similar but the current differs between fruits.

Make this project better

  1. BasicMeasure the voltage of one lemon cell.
  2. This projectBuild a lemon battery and compare fruits
  3. AdvancedMeasure current as well, and explain why the voltage is similar but the current differs between fruits.

Science fair mode

Text marked "You write this" is a prompt for your own work; everything else is specific to this project.

Problem
You write thisWrite your question as: How does [what you change] affect [what you measure]?
Hypothesis
You write thisWrite it as: If [I change this], then [this will happen], because [reason].
Variables
You write thisName the one thing you change (independent), the thing you measure (dependent) and what you keep the same (controlled).

Materials and procedure are in Materials and the Roadmap.

Observation table

You write thisDraw a table with one column for what you change, one for each repeat reading and one for the average.

Graph
You write thisPlot what you changed along the bottom and what you measured up the side; use a bar chart for categories and a line graph for numbers.
Results
You write thisState what the graph shows in one or two sentences, with numbers.
Conclusion
You write thisSay whether the result supports your hypothesis and why you think so.

Display board

  • Title and your name
  • Question
  • Hypothesis
  • Materials
  • Procedure (with photos)
  • Data table and graph
  • Conclusion
  • What you would do next

Questions judges ask

  • Which metal is the negative terminal?
  • Does the lemon supply the energy?
  • Why does one lemon not light an LED?
  • What would you change if you did this again?
  • What was your biggest source of error, and how did you reduce it?
  • Where is this idea used in real life?

Working as a team

Solo or up to 2. Suggested roles:

ResearchSetup and measurementData and graphsDocumentationPresentation

Report and presentation

Report structure

  1. Title and question
  2. Background: the science behind it
  3. Hypothesis
  4. Materials
  5. Method (steps, with a diagram or photo)
  6. Observations (table)
  7. Results (graph and calculation)
  8. Sources of error
  9. Conclusion
  10. What you would do next
  11. References

Presentation structure

  1. The question
  2. Why it matters
  3. The idea behind it
  4. Setup (photo)
  5. Method in three steps
  6. Results (one clear graph)
  7. What the result means
  8. Errors and limits
  9. Conclusion and next step

Viva questions

Try answering before you open each one.

Which metal is the negative terminal?

Zinc, which gives up electrons more readily than copper.

Does the lemon supply the energy?

No, the energy comes from the zinc reacting; the juice is the electrolyte.

Why does one lemon not light an LED?

Its voltage is below what the LED needs, so several are joined in series.

Resources

NCERT textbooksncert.nic.inPhET interactive simulationsphet.colorado.edu

Source and attribution

Original

Written by Technifyed. Free to use for your own school or college project; write the report in your own words. Added 1 Oct 2026.

Similar projects

More Chemistry projects

Chemistry · Electrochemistry

Electrolyse water and collect the gases

Split water with a 9 V battery and show that hydrogen and oxygen form in a 2:1 ratio.

  • Intermediate
  • 1 day
  • Under 250
Experiment · Basic electronicsView

Same tools

Physics · Current Electricity

Verify Ohm's law and find where it fails

Plot current against voltage for a resistor and a bulb and explain the difference.

  • Easy
  • 1–3 hours
  • Under 250
Experiment · Basic electronicsView

Electronics and Communication · Analog Circuits

Build a clap switch

Switch an LED or a low-voltage lamp on and off with a clap.

  • Easy
  • 2–7 days
  • 250–500
Hardware Project · Basic electronicsView

Chemistry · Physical Chemistry

Investigate which liquids conduct electricity

Build a simple conductivity tester and sort solutions into electrolytes and non-electrolytes.

  • Beginner
  • 1–3 hours
  • Under 250
Experiment · Basic electronicsView

Two-subject alternatives

Nutrition and Food + Chemistry

Test foods for adulteration at home

Use simple official home tests to check milk, turmeric, honey and tea for common adulterants.

  • Easy
  • 1 day
  • Under 250
Experiment · Household materialsView

Fine Arts + Chemistry

Experiment with natural pigments

Make paints from turmeric, beetroot, charcoal and soil and test how they last in light.

  • Easy
  • 2–7 days
  • Under 250
Art Project · Household materialsView

Materials, Energy and Other Branches + Chemistry

Study corrosion protection for steel

Compare paint, oil, zinc coating and sacrificial protection on steel in salt water.

  • Intermediate
  • 2–4 weeks
  • 250–500
Experiment · Household materialsView

Materials, Energy and Other Branches + Chemistry

Make and test a simple supercapacitor

Build a capacitor from activated carbon electrodes and salt water and measure its capacitance.

  • Advanced
  • 2–4 weeks
  • 500–1,000
Experiment · Lab equipment requiredView

Same difficulty and budget

Biology · Evolution

Model natural selection with coloured beads

Play predator on beads scattered on patterned cloth and watch the population shift over generations.

  • Easy
  • 1–3 hours
  • Under 250
Simulation · Household materialsView

Biology · Biotechnology

Culture yeast and measure fermentation

Use balloons on bottles to measure how sugar type and temperature change the gas yeast produces.

  • Easy
  • 1–3 hours
  • Under 250
Experiment · Household materialsView

Enter your email and the official page opens. Phone is optional.

We save your email, and your phone number if you add it, to send you this link and, if you tick the box, the weekly list. Under 18? Ask a parent or guardian first. How your details are used.

Open official page