Como funciona una resistencia eléctrica ⚡ que es una resistencia eléctrica
Summary
TLDREl guion del video ofrece una explicación detallada de cómo funciona un resistor en un circuito. Se menciona que la resistencia eléctrica es la oposición al flujo de electrones, medida en ohms, y está influenciada por el material del cable, como el cobre o el hierro. Se describen los conductores, semiconductores, aislantes y superconductores. El video también cubre cómo se calcula la resistencia usando la fórmula R = ρ(L/A), y cómo se pueden combinar resistencias en serie y paralelo para obtener valores deseados. Se discuten las aplicaciones de los resistencias, como regular la corriente y el voltaje en circuitos, y se introduce el potenciómetro como un dispositivo para variar la resistencia durante el uso. El script concluye con una llamada a la acción para apoyar el contenido y agradece a los colaboradores.
Takeaways
- 🔌 Un resistor es un componente que limita el flujo de corriente eléctrica en un circuito.
- ⚡ La resistencia eléctrica se mide en ohms y se opone al movimiento de los electrones.
- 👤 El cuerpo humano también puede conducir electricidad, por lo que en cierto sentido somos resistivos.
- 🚫 Los materiales conductores como el cobre o el oro tienen un coeficiente de resistencia bajo, mientras que los aislantes como el vidrio o el plástico tienen uno alto.
- 🤝 Los semiconductores tienen valores intermedios de resistencia y pueden variar su conductividad según factores externos.
- 🌡 Los superconductores disminuyen drásticamente su coeficiente de resistencia por debajo de una cierta temperatura.
- 📏 La resistencia de un cable se calcula multiplicando el coeficiente de resistencia por la longitud y dividiendo por el área de la sección transversal.
- 🌡 La temperatura puede afectar el valor de la resistencia y es importante tener en cuenta para la precisión.
- 🔧 Los resistencias se fabrican con diferentes métodos para obtener valores precisos y compactos.
- 🎨 El código de colores de los resistencias permite identificar su valor en ohms sin necesidad de números.
- 🔄 Se pueden combinar resistencias en serie o paralelo para obtener valores de resistencia deseados.
- 🛠 Los resistencias se utilizan para regular la tensión en los componentes de un circuito y los potenciómetros permiten modificarla durante su uso.
Q & A
¿Cómo funciona internamente un resistor?
-Un resistor funciona al oponerse al flujo de electrones al aplicar una diferencia de potencial o voltaje entre los dos extremos del cable. La resistencia eléctrica, medida en ohms, es la fuerza que impide el paso de los electrones a través del material del cable.
¿Qué son los electrones y cómo se relacionan con el corriente eléctrica?
-Los electrones son partículas subatómicas con carga negativa que pueden moverse libremente. Cuando se aplica una tensión eléctrica, los electrones son empujados a moverse, lo que se conoce como corriente eléctrica.
¿Qué es la resistencia eléctrica y cómo se mide?
-La resistencia eléctrica es la oposición al flujo de electrones a través de un material y se mide en ohms. Es determinada por el coeficiente de resistencia del material del cable.
¿Cómo afecta el coeficiente de resistencia de un material a su capacidad para conducir la electricidad?
-Un material con un bajo coeficiente de resistencia es un conductor, como el cobre o el oro. Un material con un alto coeficiente de resistencia es un aislante, como el vidrio o el plástico, y hay materiales semiconductores con valores intermedios que pueden variar su conductividad dependiendo de factores externos.
¿Qué son los superconductores y cómo se diferencian de otros materiales?
-Los superconductores son materiales que, por debajo de una cierta temperatura, reducen drásticamente su coeficiente de resistencia. A diferencia de otros materiales, su resistencia eléctrica se anula casi por completo.
¿Cómo se calcula la resistencia de un cable según su material, longitud y área de corte transversal?
-La resistencia de un cable se calcula multiplicando el coeficiente de resistencia del material por la longitud del cable y dividiendo por el área de su corte transversal.
¿Cómo afecta la temperatura a la resistencia de un cable?
-La temperatura puede afectar el valor de la resistencia, ya que el coeficiente de resistividad que se encuentra en las tablas se especifica a una temperatura determinada. La mayoría de los metales aumentan su coeficiente de resistividad al aumentar la temperatura.
¿Qué es el efecto Joule y cómo se relaciona con la generación de calor en un conductor?
-El efecto Joule es el fenómeno por el cual un conductor emite calor cuando una corriente eléctrica pasa a través de él. La energía disipada en forma de calor se puede calcular como la multiplicación entre el voltaje aplicado al conductor, la intensidad de la corriente eléctrica y el tiempo que ocurre este evento.
¿Cómo se crean resistencias con valores precisos y cómo se controla su tamaño?
-Existen diferentes métodos para crear resistencias con valores precisos, como el uso de un alambre de níquel enrollado en un tubo de cerámica, el uso de un material compuesto en un volumen definido o el uso de un cilindro de cerámica cubierto por una película de carbono que se corta en espiral hasta obtener la resistencia deseada.
¿Qué es el código de colores de un resistor y cómo se utiliza para determinar su valor en ohms?
-El código de colores es una convención utilizada para identificar el valor de resistencia de un resistor sin necesidad de números. Cada color representa un dígito o un multiplicador, y la combinación de colores en las bandas del resistor permite determinar su valor en ohms.
¿Cómo se conectan resistencias en serie y paralelo para obtener un valor de resistencia equivalente?
-Al conectar resistencias en serie, la resistencia equivalente es la suma de las resistencias conectadas. En cambio, al conectarlas en paralelo, la resistencia equivalente es la inversa de la suma de las inversas de las resistencias, lo que reduce el valor total de la resistencia.
¿Para qué se utiliza un potenciómetro en un circuito y cómo funciona?
-Un potenciómetro se utiliza para modificar el voltaje que pasa a través de un componente durante el uso del circuito. Funciona con un resistor de forma arco, y al tener un punto de contacto entre sus extremos, actúa como si tuvieran dos resistencias en serie, permitiendo medir diferentes valores de resistencia al cambiar la posición del contacto.
¿Cuáles son las leyes de Kirchhoff y cómo se relacionan con el funcionamiento de un resistor?
-Las leyes de Kirchhoff son principios fundamentales en la electrónica. La ley de Kirchhoff de los voltajes establece que la suma de voltajes en un camino cerrado en un circuito debe ser cero. La ley de Kirchhoff de las corrientes indica que en un nodo, la corriente que entra debe ser igual a la que sale. Estas leyes, junto con la ley de Ohm, son claves para entender y calcular el comportamiento de un resistor en un circuito.
Outlines
🔌 Funcionamiento interno del resistor
El primer párrafo explica cómo funciona un resistor internamente. Comienza con la concepto de electricidad, utilizando un cable como ejemplo, que contiene electrones con carga negativa y pueden moverse libremente. Cuando se aplica una diferencia de potencial o voltaje, los electrones se mueven, lo que se conoce como corriente eléctrica. Sin embargo, hay una resistencia que se opone al flujo de electrones, llamada resistencia eléctrica, medida en ohmios. El cuerpo humano también puede conducir electricidad, por lo que podríamos ser considerados un resistor. La resistencia varía según el material, con conductores como el cobre y el oro que tienen un coeficiente bajo, aislantes como el vidrio o plástico con coeficiente alto y semiconductores con valores intermedios que cambian su conductividad según factores externos. También se mencionan los superconductores que disminuyen su coeficiente de resistencia drásticamente a ciertas temperaturas. La resistencia de un cable se calcula multiplicando el coeficiente de resistencia por la longitud y dividiendo por el área de la sección transversal. Se usan analogías como un tubo con partículas para entender cómo afectan cada variable. La temperatura también puede afectar el valor de la resistencia, y es importante evitar cortocircuitos al usar cables entre dos pólos de una fuente de energía.
🌡 Efecto Joule y creación de resistencias
El segundo párrafo habla sobre el efecto Joule, que es cuando un conductor emite calor al pasar una corriente eléctrica. El calor generado se calcula multiplicando el voltaje, la intensidad de la corriente y el tiempo. Se menciona que los materiales como el Nichrome, con alto punto de ebullición y resistencia, son adecuados para resistencias que generan calor. Para crear resistencias con un valor de ohmios específico, se pueden usar diferentes métodos: un alambre de níquel enrollado en un tubo de cerámica, un material compuesto con elementos que varían el coeficiente de resistencia, o un cilindro de cerámica cubierto por una película de carbono que se corta en espiral para obtener la resistencia deseada. Se explica el código de colores de los resistores para determinar su valor en ohmios y su tolerancia, y se menciona que no hay resistores de todos los valores, por lo que se pueden combinar en serie o en paralelo para obtener valores de resistencia deseados. También se mencionan las leyes de Kirchhoff y la ley de Ohm para entender el funcionamiento de los circuitos eléctricos.
🎛 Potenciómetro y su uso en circuitos
El tercer párrafo se centra en el potenciometro, un dispositivo que permite modificar la resistencia y, por lo tanto, la tensión en un circuito durante su uso. Funciona con un resistor de forma arco, con un punto de contacto que actúa como si tuvieran dos resistores en serie. Esto permite medir diferentes valores de resistencia dependiendo de dónde se tome la medición. Se ilustra cómo el potenciometro puede usarse en un circuito para variar la tensión que pasa a través de un LED, permitiendo controlar la intensidad de la luz o la temperatura de un dispositivo. El video concluye con un agradecimiento a los que han seguido el contenido y un recordatorio de la cantidad de trabajo que implica crear un video educativo de esta naturaleza.
Mindmap
Keywords
💡Resistor
💡Electricidad
💡Corriente eléctrica
💡Resistencia eléctrica
💡Coeficiente de resistencia
💡Conductor
💡Insulador
💡Semiconductor
💡Superconductor
💡Efecto Joule
💡Potenciometro
💡Ohm's Law
💡Código de colores
Highlights
A resistor's function is explained by understanding the concept of electricity and the movement of electrons.
Electric current is the movement of electrons caused by a potential difference or voltage.
Electrical resistance opposes electron flow and is measured in Ohms.
The human body, like a resistor, can conduct electricity due to its resistance.
Different materials have varying coefficients of resistance, classifying them as conductors, insulators, semiconductors, or superconductors.
Copper and gold are examples of materials with low resistance coefficients, making them good conductors.
Materials like glass or plastic have high resistance coefficients, classifying them as insulators.
Semiconductors have intermediate resistance coefficients and can vary their conductivity based on external factors.
Superconductors drastically decrease their resistance below a certain temperature.
The resistance of a cable is calculated by the material's resistance coefficient, length, and cross-sectional area.
An analogy of a pipe with particles helps visualize how different variables affect resistance.
Temperature affects resistance values, and resistivity coefficients are temperature-dependent.
Resistors are created using various methods to achieve desired Ohm values, such as nickel wire in ceramic tubes.
Composite materials and carbon film on ceramic cylinders are used to create resistors with precise values.
A color code system allows determining resistor values without numerical markings.
Resistors can be combined in series or parallel to achieve desired resistance values.
Resistors are used to regulate voltage in circuits, protecting components like LEDs from burning out.
Kirchhoff's laws and Ohm's Law are fundamental in calculating resistance values in circuits.
A potentiometer allows dynamic voltage adjustment in a circuit using an arc-shaped resistor.
Transcripts
it is likely that they have ever seen a resistor like this in a circuit
or even in a heater
but how does a resistor works internally?
first we must clarify the concept of electricity
and for this we are going to use this piece of cable
this cable has electrons, which are sub-atomic particles of negative charge
and that they can move freely.
when a potential difference or voltage is applied between the two ends of the cable
the electrons are forced to move
and it is to this movement that it is known as electric current.
however, even though the electrons can move through the wire,
not everything is so easy
there is a resistance that Opposes the flow of electrons
this is: the electrical resistance, and its unit of measurement is the Ohm.
In fact, since our own body is capable of conducting electricity
We could say that we ARE a resistor,
and even that in these two circuits the resistance is equivalent
but clearly one of the two options is more viable to implement.
One of the main differences is that each one has a coefficient of resistance
determined by the material of which they are made
in fact, there are multiple classifications depending on this coefficient of resistance
If a material has a low coefficient of resistance
it is said that this is a conductor, such as copper or gold.
On the contrary, if its coefficient is higher, it is said to be an insulating material
such as glass or plastic
but there are also materials with intermediate values, and these are known as semiconductors,
which, in some cases, vary their conductivity depending on other external factors
as we saw in the previous video about diodes.
and finally, although they are an extreme case,
there are also superconductor materials
which when they are below a certain temperature
decrease their coefficient of resistance drastically
we now know roughly how the coefficient of resistance affects the behavior of the material
And if one day we find two cables of exactly the same dimensions
but made of different materials, such as: one copper and one iron.
after having seen a table like this, we could say with complete certainty
that the resistance of the iron cable is greater.
but, we could not say what is the value of the resistance of any of the two cables
because only that information is not enough to know.
let's focus on the cable copper.
The resistance of this cable will be equal to the coefficient of resistance
multiplied by the length of the cable and divided by the area of its cross section
let's make some analogies to understand more easily how each variable affects.
let's imagine that this cable is a pipe
to which we will add two tanks, one filled with particles that represent the electrons
and an empty one, to also represent the potential difference or voltage that will be applied to the cable,
when we close the circuit and let the current pass
we can see how the particles pass without problems towards the other tank
this, because copper has a fairly low resistivity coefficient
Now, if we change the copper for another material like iron
the pipe will have obstacles inside, in this way, when we let the current pass,
it will be more difficult, but not impossible it reaches the other end.
that is, it will have a greater resistance.
having an insulating material would be like having the pipe completely covered
the next two variables are easier to understand
if we have a greater distance to travel in the pipeline
it is logical that more time and effort is required to get to the other extreme
that is, the longer the cable, the greater the resistance.
On the other hand, if we increase the diameter of the pipe,
even when the resistivity coefficient continues to affect the entire volume
There are going to be more possible ways for electrons to pass.
in other words, the greater the cross-sectional area of the cable
there is less resistance to the passage of the current.
Now let's go back to the real version before my computer melts by doing these simulations.
although this formula is usually used for its simplicity
you should know that the temperature can also affect the value of a resistance
since the coefficient of resistivity you find in the tables like this
specify the temperature at which that value is correct.
although most metals increase their resistivity coefficient by increasing their temperature
this is not true for all materials
It's important to mention that in reality
almost never will have only one cable between the two poles of a power source
as this could generate a short circuit,
that is, a sudden increase in the amount of current that passes through the conductor
I say almost, because when you want generate heat, as for example in a heater,
basically that is what is done.
To this phenomenon by which a conductor emits heat when a current passes through the
It is known as the Joule effect.
and we can calculate the energy dissipated in the form of heat
as the multiplication between the voltage applied to the driver
the intensity of the electrical current that is happening
and the time during which this occurs.
The limitation of doing this is that the material could be melted
or oxidize extremely fast, leaving it unusable
That is why for such cases, alloys such as Nichrome are usually used
which, in the first place, has a melting point of 1400 ° C
and also has a high coefficient of resistance
this last characteristic is precisely the reason why only that section is heated
and not the cable that we plugged in.
going back to the main topic.
Now that we know how to get a quantity of Ohms to our liking
in theory we could create our own resistance
using an extremely thin material with a high coefficient of resistance
but in reality they are not like that
if they were just a wire
It would be extremely difficult to get an accurate resistance in such a small size.
There are different ways to create a resistance depending on how many Ohms you want to get
and how accurate is its value.
The first way is using a nickel wire wound in a ceramic tube
which by the way is an insulator
in this way, you can control the total resistance
modifying the length of the cable, but maintaining a compact size.
the second option is using a composite material in a defined volume
but that by varying the elements that make it up
you can vary its coefficient of resistance and therefore the resistance of the resistor.
and the third option, is by means of a ceramic cylinder covered by a carbon film,
which is cut in a spiral until obtaining the desired resistance.
in other words
a carbon wire is gradually created to increase the resistance to the desired value
Aa generally these resistances are so small
It would be quite difficult to print what their value is,
that's why was invented a code of colors
by which we can know its value in Ohms, even without numbers
for example, this is a resistor of 200 kilo Ohms,
The way to read its value is as follows:
the first and second bands correspond to digits from 0 to 9
in this case red is 2 and the black is 0
then, the third band corresponds to a multiplier
to avoid the need to put many black bands when representing large values
in this case, the yellow band means that you have to multiply by 10000
so
2 0 per 10000 gives us 200000 ohms or 200 Kilo omhs.
and the last band that is left corresponds to the tolerance of this value
Well, as we saw earlier, a lot of precision is required to generate an exact value.
in this case, gold means that the tolerance of the value is ± 5% of the defined value.
may happen that at some point you will find a resistor with more bands
and its reading will vary slightly, but the logic is the same
If you search for "color resistance code" on Google you will find many options to download.
but I also wanted to make one for you and you can download it for free on my Patreon page
As you can imagine, it is unlikely that there are resistors of all values,
so there are different ways to mix known resistors to get a desired value
the first way is connecting resistors in series
whereby the value of the equivalent resistance is equal to the sum of the connected resistors.
this is very easy to remember if we think about the formula that we saw at the beginning
by connecting two equal resistors in series
the only thing we are doing is multiplying the length of the cable by two
and therefore its value will be double
On the other hand, if we want to reduce the total resistance of a set of resistances
what we can do is connect them in parallel.
if we connect two equal resistances in parallel and think again in the formula,
we will realize that what we are doing now
is simply multiplying the cross-sectional area by two
that is, we are going to have half the resistance.
for more complex systems the way to calculate it is something like this
but the important thing is that you understand why it is like that.
At this point I think you are ready to start talking about what a resistance is for.
the use of a resistance with a static value in a circuit
allows us to regulate the voltage that will be generated in different components
suppose we have a battery of 12 Volts and an LED that works at a maximum of 3 Volts
If it exceeds this value, it will burn.
in this extremely simple circuit
just by putting a resistance of the right value we can make exactly 3V pass through the LED
In this video I do not want to go into much detail about how to calculate the value of the resistance that we would need
but, if you want to continue on your own, I summarize 3 extremely important laws
the first is Kirchhoff's voltage law,
which tells us: that if we add all the voltages following a closed path in a circuit
the value must be zero
or in other words, the sum of the voltage in each of the components in this trajectory
must be equal to the voltage in the power source that is supplying them.
the second, is the current Kirchhoff law,
which tells us that in each node, that is, where there is more than one possible path for the current
the current that enters must be equal to the one that comes out.
and finally the third law is Ohm's Law
which tells us that the voltage in a component is equal to the current that passes through the
multiplied by its resistance
which by the wayz allows us to calculate any of the three variables
as long as we have the other two.
as I said, a resistance allows us to control the voltage that passes through other components,
and there will be times when we want to modify that voltage during the use of the circuit,
not only during the design stage.
and this is where the Potentiometer appears.
the way a potentiometer works is using an arc-shaped resistor
which, by adding a point of contact with another terminal right between its ends,
act as if they had two resistors in series.
in this way, if we measure the resistance between the first terminal and the intermediate one, we will obtain a value,
whereas if we measure the third terminal and the intermediate we will obtain another value.
however, by measuring the resistance between the first terminal and the last
This will always be the same, since being in series must be added.
this feature allows us to generate circuits like this
in which when changing the potentiometer we vary the voltage that passes through the LED
This video had a lot of information, so congratulations if they got here
Take it easy and everything is going to make sense
make a video like this equals about 30 or 40 hours of work
including research, script, animation and editing, among other things
so, if you think what I'm doing is worth it, you could consider supporting me through Patreon
as always, thanks to facebook pages
Mecatronica, We are mecatronica and the electrician's blog, for always sharing my content
That's all for now and I'll see you in the next chapter
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