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electrical circuits

Definition

Electricity is the sub-discipline of physics that deals with electric charge and its applications:

• Electric charge and energy are stored in a power source, such as a battery. Electric charge can be either “positive” or “negative”. In a rechargeable battery, the energy comes from charging the battery.
• A device is the machine that uses the electrical power: A lamp lights up, a motor turns and is able to perform work.

•  A circuit is created when the electric charge flows between two poles – a plus pole and a minus pole. The electric charge flows from the power source to the device and back. The energy flows with the current and is used by the device for its specific purpose. This is why batteries eventually run out (discharge).
• The current flows through electrical wires, such as a piece of metal in the form of a cable.
• Electric switches are used to control the flow of current. They connect or interrupt the current flow. This allows us to turn a torch or a motor on and off.

Electric current can transport energy very quickly across vast distances, and use it for a wide range of different purposes. That makes it versatile, and more useful than almost anything else on earth.

History

Without knowing it, people were able to observe a very impressive electrical phenomena even tens of thousands of years ago: Lightning during a rainstorm. During this phenomena, a very large amount of electric charge flows with a very large amount of energy from the clouds and into the ground in a fraction of a second. The effect is so strong that trees can essentially “explode”, because the energy released during the lightning strike is great enough to cause the water stored in the tree trunk to suddenly boil, and the wood to burst.

However, we have all probably had harmless experiences with electricity, such as when you comb your hair with a plastic comb and then see it “standing on end.” The hair is electrically charged due to the friction on the comb. Such effects were observed as early as 600 BC in case of friction with amber.

An early forerunner of the “battery” was produced during the last century BC: Two rods, one iron and one copper, were immersed in an electrolyte, as it is known today. At the time, grape juice was used for the electrolyte!

It has only been in the last approx. 400 years that electricity has been investigated systematically. Around the beginning of the 19th century, the interaction between flowing electric current and magnetism was discovered – the basis for later electric motors. British physicist Michael Faraday summarised the natural laws of electricity in mathematical formula. These made it possible to quantitatively calculate electrical phenomena.

Since that time, people have been gaining experience with electricity and creating new practical applications. New discoveries are moving faster and faster all the time. Think of the incandescent light bulb, the first telegraph, the first radio transmission, telephone, TV, electric trains and other vehicles, the pocket calculator – even up to telecommunications satellites, smartphones, microcontrollers and huge computing centres.

Fundamentals

The following components are used for an introduction to electricity and electrical engineering with fischertechnik:

• The battery holder contains a 9 V block battery or rechargeable battery. It has an on/off/reverse polarity switch.
• An LED serves as the light source.
• A powerful, small, quiet electric motor to power the model. Since this is a direct current motor, its rotational direction can be changed by changing the polarity (reversing the connections).

• The fischertechnik button is a self-resetting switch that changes a “central” contact from a “break” contact to a “make” contact at the push of a button. It can be used to not only turn devices on and off, but also build refined control devices using suitable electrical switches.
• Cables with plugs are used to create the electrical connections between components.

Of course, all of these fit perfectly into the fischertechnik system, and can be used to not only illustrate basic electrical functions, but also create robust and realistic functional models of machines.

Further information

On electricity in general:

Center for Educational Media on the Internet e. V

Electrical engineering with fischertechnik:

Download: Construction manual