Battery
Battery is a device that stores energy and releases it as electricity to power things.
A sealed jar holds marbles inside it. When you open the lid, marbles roll out and push things, fill gaps, or move small objects. The jar is the battery and the marbles are the stored energy. Once all the marbles are out, the jar is empty and nothing moves until you refill it.
Explaining battery by grade level
A lemon can work like a battery. You push two different metals into the lemon. The juice inside helps move tiny bits of energy from one metal to the other. That moving energy is what we call electricity.
Projects that explore battery
Every battery stores energy through a chemical reaction between two different materials. A potato contains moisture and acid that can trigger this same reaction. Push two different metal strips — copper and zinc, for example — into a potato, connect a multimeter, and you can read the voltage each metal combination produces. Different pairs generate different amounts of power. Wire two or more potatoes in series and their voltages add together. With the right combination, four potatoes can produce enough current to light two low-power LEDs.
A battery stores energy through internal chemical reactions, and temperature changes how fast those reactions run. When the reaction slows, the battery powers a device for less time. You test three brands of AA batteries — Energizer, Duracell, and Eveready — at room temperature (24°C), freezing (0°C with ice cubes), and extreme cold (-78°C with dry ice). Each battery is sealed in a plastic bag with jumper wires, placed in a beaker at the target temperature, then connected to a small table fan. You time how long the fan runs before the battery dies. Comparing results across temperatures and brands reveals which batteries hold up best in harsh conditions.
Temperature affects how efficiently a battery releases its stored energy. To find out by how much, you test three brands of AA battery — Energizer, Duracell, and Eveready — at 18°C, 22°C, and 26°C. Each battery powers an identical small table fan, and you time how many minutes the fan runs before each battery dies. An air conditioner holds the room temperature steady during each test. As it turns out, temperature makes only a small difference. Across all three temperatures, the Energizer battery lasts the longest and the Eveready runs out first.
A lemon works as a simple battery because it contains citric acid, which carries an electric charge between two different metals. The acid reacts with each metal differently, and that difference creates a flow of electrons — the tiny charged particles that make up electricity. Push a copper piece and a zinc strip into a lemon, then connect the two metals to a small LED. The question is whether the current the citric acid drives through that circuit is strong enough to make the LED glow. It's the same basic idea behind commercial batteries, just with fruit instead of a sealed case.