Two metals and a liquid
Show on a big screenA row of lemons can light an LED. An LED is a small lamp. It glows only when current enters it the right way round. Where does the current come from?
- A lemon with a copper strip and an iron nail.
- The juice is the electrolyte. The strip and nail are the electrodes.
- A reaction happens where the metals meet the juice. That makes current.
- Salt water is an electrolyte too.
A cell makes electric current from chemicals. Each lemon, with two metals in it, is a cell. A simple cell has two different metals, called electrodes. Both dip into a liquid called an electrolyte. A chemical reaction is a change that makes new substances.
One lemon is a weak cell. A row of cells pushes the current harder.
The rule
A simple cell has two different metals dipped in a liquid electrolyte. A chemical reaction where the metals meet the liquid makes current. When its chemicals are used up, the cell is dead.
| Part | In the lemon cell |
|---|---|
| Electrodes | A copper strip and an iron nail |
| Electrolyte | Lemon juice, or salt water |
| Pure water | Not an electrolyte, so no current |
A teacher or an adult sets up real cells and circuits. Never open a cell.
Read each setup. Will the LED glow?
Loading lab…
Try the lab to finish this lesson.