Electricity Week 1. Batteries

Crayon Box Electricity Week 1 Battery

Everyday we use various types of batteries without knowing much about how they work. Our very first ‘Electricity Week’ is dedicated to the simplest kind of battery – the voltaic cell. We start off with a scientific explanation and then move on to the experiment portion, where we describe fun and engaging projects you can do with your kids.

A SIMPLE BATTERY

A simple battery is comprised of three parts: two electrodes made of different metals, and an electrolyte (usually a liquid) that reacts with them.

Simple battery makeup

Simple galvanic cell makeup

HOW DOES IT WORK?

“The battery generates current when one electrode (the anode) dissolves more easily in the electrolyte than the other electrode (the cathode). The dissolved atoms enter the electrolyte as positive ions, leaving some excess electrons behind on the anode. When a wire is connected between the anode and the cathode, the excess electrons redistribute themselves and some of them flow through the wire to the cathode, thereby producing an electric current.”

Battery Basics, sciphile.org

Now, how can you explain this to a 5-year-old? Assuming that your child already knows the story about electrons that live inside wires, you can explain the reason why these tiny guys want to travel from one electrode to another. Due to a chemical reaction, one electrode (the anode) becomes the birthplace of new electrons. At the same time, another electrode (the cathode) becomes a highly attractive place for the electrons to reside. A wire connecting the electrodes works as a path for the electrons. When electrons pass through the wire, we call that an electric current.

The idea of electrons traveling in search of a better place can be expanded further to explain other characteristics of batteries, such as voltage, current, and capacity. However, making up a good child-friendly story takes some serious preparation. Check out this great article about batteries.

BATTERY MATERIALS AND PERFORMANCE

The voltage of the battery depends solely on the chemistry between the electrodes and the electrolyte. This means different materials will provide different levels of voltage. The highest voltage is achieved when: 1) the anode is strongly reactive with the electrolyte, and 2) the cathode has the weakest reactivity with the electrolyte it is immersed in.

Which materials can be used for homemade batteries? For the electrodes you can use zinc, aluminum, copper or steel. Weak acids (e.g. citric, acetic, or phosphoric) or a salt-water solution can be suitable for the electrolyte. Zinc is the best anode material. Copper and stainless steel both make good cathodes.


SOURCES FOR COMMON ELECTRODES

Sources for common electrodes

SOURCES FOR COMMON ELECTROLYTES

SOURCES FOR COMMON ELECTROLYTES


The highest voltage (about 1.2 volts) can be achieved with zinc, stainless steel and phosphoric acid.

The maximum available current is difficult to predict because it depends on various parameters, such as the size and proximity of electrodes, as well as the concentration of the electrolyte. In order to get higher currents, use larger electrodes, placed closer to each other, immersed into a more concentrated electrolyte.

Lastly, the capacity of the battery depends on its size. Larger sizes of electrodes and larger volumes and concentrations of electrolytes last longer.

HOMEMADE BATTERY PROJECTS

DIY battery projects isn’t just fun for kids. Set a goal to make the most efficient battery in terms of: 1) highest voltage, 2) highest current, or 3) highest capacity.

Check out these common types of homemade batteries and learn how to make them.


THE COKE CAN BATTERY

Anode: a strip of aluminum from a soda can.
Cathode: a piece of thick copper grounding wire.
Electrolyte: Coke or any other soda.
Voltage: approximately 0.75 volts.
Max current: about 3 mA.

Coke can battery

Battery made using a strip of aluminum from a soft drink can, a piece of copper grounding wire, and a glass of Coke. Produces 0.75 volts and a maximum of about 3 mA. Credit

More about coke can batteries:
http://sci-toys.com/scitoys/scitoys/echem/batteries/batteries.html


THE LEMON BATTERY

Anode: a zinc washer.
Cathode: a copper penny.
Electrolyte: Coke or any other soda.
Voltage: approximately 1.0 volts.

Three lemon batteries connected in series with an LED. Each battery uses a zinc washer for the anode and a penny for the cathode. Together, the three batteries produce a little over 2.5 volts and maximum of about 0.1 mA.

Three lemon batteries connected in series with an LED. Each battery uses a zinc washer for the anode and a penny for the cathode. Together, the three batteries produce a little over 2.5 volts and maximum of about 0.1 mA. Credit

More about lemon batteries:
http://www.techagekids.com/2013/07/making-lemon-battery-and-how-does-it.html


THE VOLTAIC PILE

Anode: a zinc washer.
Cathode: a copper penny.
Electrolyte: vinegar.
Voltage: approximately 0.5 volts.

Soak a piece of paper or cardboard in vinegar and sandwich between a penny and a zinc washer to create battery. Stacking many of these battery cells in series, one on top of the other, creates a “voltaic pile”.

Voltaic pile made from a stack of pennies, zinc washers and vinegar-soaked paper stickers. The stack is housed in a plastic coin tube of the type used by coin collectors. Twenty cells are stacked to produce 15 volts and a maximum current of about 0.2 mA.

Voltaic pile made from a stack of pennies, zinc washers and vinegar-soaked paper stickers. The stack is housed in a plastic coin tube of the type used by coin collectors. Twenty cells are stacked to produce 15 volts and a maximum current of about 0.2 mA. Credit

More about penny battery:
https://en.wikipedia.org/wiki/Penny_battery


Some items you can connect to your battery include: LEDs, low power light bulbs, and calculators. Digital multimeters can be used to measure voltage and current.

THERE’S AN APP FOR THAT!

How to Make Electricity is a virtual lab where kids can get their hands on various experiments on generating electricity.

Our app ‘How to Make Electricity’ is a virtual lab where kids can get their hands on various experiments to generate electricity. The app features a set of adapted, child-friendly, interactive physical models. If a real coke can battery can light up only a tiny LED, the voltaic cell in lab #1 of our app can make a pickle glow.


AppStore

Download the ‘How to Make Electricity‘ app from the App Store.
Download free lite version of the ‘How to Make Electricity’ app.

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