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Electronics 3



We're not quite that far yet. Let's start with a simple circuit and try, using it, to explain the basic terms. First of all, the above picture represents a electricity source, with one consumer. In the circuit there is an Ampere- meter which, providing it's own resistance is very small, will measure the flow of current, but will not influence it. This is why it is always placed in the circuit, so that it registers the total current. In this case, one also speaks of a serial circuit.

The units in electronics are nearly more important than the other disciplines. This is also because some of them cover very large areas, from pico (0,000.000.000.001) up to tera (1.000.000.000.000). If you are not familiar with the various prefixes, you can find out what they mean here. The current strength is possibly measured in A(mpere) and the identifier is shown as 'I'.


This picture shows, how the voltage is measured. To do this, the measuring device is connected in parallel. If one wishes to determine the voltage delivered by the current source, this must be done before and after the source.


The next picture shows several serially connected consumers. On each consumer there is a voltage. The voltage is measured using the method shown in the picture. If otherwise, no major resistance exists, the sum of the individual voltages should correspond to the voltage at the source.

Whereas the voltage with the identifier 'U' and the unit V(olt) is measured, the resistance has the identifier 'R' and the unit (Ohm). This is the result of the measuring of voltage and current strength, which when divided by each other, provide the resistance. Basically, all the components in a circuit, set off a current flow against a resistance, which, we'll neglect at the moment, in favour of progressing a bit faster.


Here, one can follow the breaking down quite well. In this simple calculation, at the current source there are 12 V, which divide themselves into 2 V and 10 V respective to the resistances of the two consumers. Thereby, it doesn't matter whether it's a resistance or a lamp, a current of 1 A still flows.

More about parallel- and serial-switching

At first glance, a circuit often looks as if only either the full current flows, or none at all. Indeed, as a rule, this is not the case. It starts as soon as it is switched on. Although basically, a switch only has two states, on or off, indeed one must consider, that this changes from being switched on and being switched off any number of times. Light, also in a perfectly normal household, is switched on several times, before it finally lights up. The same thing then happens when it's switched off again.

Through this, you may be able to grasp, just how fast electricity is. Only the speed of light is much faster. By the way, when a light-bulb is switched on, the flow of electricity is by no means constant. At the moment of switching, about 10 times as much current is used, until the light-bulb reaches it's operating temperature. Also when charging a battery or an an accumulator no stable condition exists, because actually, the more charge the battery takes on, the lower the current flow is.

Testing modules using X-Ray technology ...








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