Unit 21 Reading Activity

Listen to the recording as you read the text. Then complete the activities.

Basic electronic components

Nowadays most of us cannot imagine life without the electronic devices which surround us. They are everywhere, and often we even forget about their existence: mobile phones, TV sets, mp3 players, electronic watches or even alarm clocks. Most people do not reflect on how and why these everyday appliances work. But being a geek requires at least some basic technical knowledge about the surrounding world.

As you probably remember from early science lessons, the electric current is an organized flow of electrons and ions in a conductor. But to make those tiny particles move, there must be some kind of force.

In electronics, this force is called an electromotive force or EMF, which may be also described as voltage. For some, the definition of voltage as the difference of potential in the conductor may be a bit hard to imagine.

So to visualize this process, you may think of the difference in the number of electrons in the conductor. If there are fewer electrons in one part of a wire than another part, then there is a difference of electrons between points A and B of the [electrical circuit].

Nature is organized in such a way that it aims at making this potential equal in both points of the circuit. So to make it equal, there is a need to move some of the electrons from one place to another. Current is exactly what we call this movement.

Of course we need to take our voltage from some electric source. One common source of power in smaller home appliances is batteries, or voltaic cells. The energy stored in batteries comes from chemical reactions that take place inside. But quite often we may replace the batteries with another source of energy, such as a solar cell, which may be found in simple calculators or electronic watches.

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