What are resistors used for?
Of course, this question does not mean social resistance, but physical resistance. But what is the function of these electrical components - what are they used for?
Resistors - familiar electrical components
Regardless of whether it is a school experiment or a hobby electronics technician: Many people know resistors as electrical components. This can be a very large sliding resistance in a school experiment or small cylindrical parts with a printed color code.
- What all these parts have in common is that they - as the name suggests - offer a resistance to the current, i.e. the movement of the charged particles in the electrical line is hindered. As a model, you can imagine that the rectilinear movement of the (electrically negative charged) electrons, for example in a solid, are disturbed by constant contact with the atoms will.
- But liquids and gases can also represent resistances for the flow of current. During a thunderstorm, for example, a certain amount of charge must build up before the air flashes over. Air also has a resistance - depending on its composition, temperature, density and humidity.
- Solids with low resistance, such as silver or copper, are good conductors. Styrofoam, glass and many Plastics have a large resistance and are therefore used as insulators.
What are resistors in a circuit for?
The question of what resistors are used for in a circuit is entirely justified. Because from what has been said so far, the situation could appear to you in such a way that resistance tends to be a hindrance (and therefore to be avoided). So what do you need them for?
The resistance of an incandescent lamp changes with temperature - experimentally one can ...
- A circuit in everyday life without any resistance would not be possible. There would be a short circuit and the fuse would blow.
- The reason is that at a given voltage, the resistance in the circuit determines the magnitude of the current flowing, true to Ohm's law U = R * I and transformed into I = U / R. If the resistance is very small, a large current flows; if the resistance is high, the current flowing is small. In the case of R = 0 there is the short circuit mentioned above.
- You are probably familiar with this regulating fact from school: a sliding resistance influenced the current I at a given voltage U (and you could use Ohm's law in a series of measurements derive).
- So-called consumers also need a resistor. Without resistance, an iron or stove top could not get hot, and an incandescent lamp could not produce light (and heat).
- Ultimately, the AC resistances of coils and capacitors determine the properties of circuits found in electrical components.
Resistance, like friction, is sometimes desirable, sometimes undesirable. But electricity without resistance? This fact actually exists. At very low temperatures, so-called superconductors only offer a negligible resistance to the flow of current. These special conductors are used, for example, to generate very large magnetic fields in particle accelerators.
