Resistance is the most common component in electronics. This device hinders the flow of current, which limits the current in the circuit and the size of the set current. Resistance to current is measured in ohms. The higher the ohmic value, the greater its hindrance to electron flow. Here is a more humorous piece of resistance. I am a resistor, English name R. As the name suggests, I was used to hinder the movement of electric currents. However, in fact, I was basically used by electronic engineers to conduct electricity, that is, let the charge flow from me. Charges flow from us and form currents. This is the same thing as the flow of water through a water pipe. Of course, to allow water to flow in the water pipes, water pressure must also be applied. The greater the water pressure, the faster the flow, ie, the greater the flow of water. The same goes for current. To make the charge flow in the conductor, there must be a voltage. The higher the voltage, the faster the charge will flow and the greater the current. The thickness of the water pipe also affects the size of the water flow. Similarly, the size of the resistor also affects the size of the current. A large resistance, like a thin water pipe, has a small current at the same voltage; a small resistance, like a rough pipe, and a large current at the same voltage. The capacitor brothers once said to me, "People will always remember you well." I used to always believe deeply, but now, I started to shake - because we are all used to conduct electricity, but we call resistance! We have been given the title of resistance, which is an ancient and wonderful thing. Although we will hinder the movement of current to a certain extent, in essence, we are still conducting. In this sense, it is more appropriate to call me conductance. But no way, people have to bow their heads under the eaves and can only get rid of their teeth and swallow them. I have a feature that when it conducts electricity, it will hinder the movement of the current to a certain extent (there are very few conductors that really do not hinder the movement of electric current!). The pressure drop is a shorthand for voltage reduction (shorthand is a common trick for people to be lazy). In order to indicate the magnitude of our current blocking effect, people introduced the physical quantity of resistance. The greater the hindrance to the current, the greater the resistance, the smaller the hindrance, and the smaller the resistance. At the same time, lazy people also regard the word “resistance†as my name, which is exactly the beginning of an eternal adventure. In fact, I once again stated that I was actually used to conduct electricity. Therefore, I hope that others will call me “electricity conductionâ€. I think the name "conductivity" is very handsome. The "directors", "guides", and "mentors" are all called "X-guides," and they all seem to have great benefits. There is one unit for any physical quantity. I also have a unit called Ohm. Speaking of the origins of ohms, there is still a love story. In Germany, a guy called ohms "discovered" (in fact, I was dreaming for him) that the current flowing through the conductor is proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor. People call this law Ohm's law. Please note: The description here uses "conductors," which again corroborates what I should call "conductivity" from historical data. In order to commemorate Ohm, people call the unit of resistance ohms, abbreviated as Europe, sometimes expressed by the Greek letter Ω, or the name ohm of the foreign gas point. It is said that when a man makes a woman happy, a woman will shout ohm's name. But what I never wanted to understand was that these men were very excited when they listened to their own women shouting at the names of other men. Sometimes men will send thousands of Euro (LV) LV bags to lovers, although electronic engineers are more bitter B, but they are sometimes very sentimental, such as sending a few thousand ohms to the girlfriend. In short, women like "Europe" very much, whether it is in a shopping mall or a bedroom. With the European unit, I also feel unique as a resistor, because people always think of you or call you at many times. How big is 1 ohm? When the voltage applied to me is 1 volt and the current flowing through my body is exactly 1 ampere, then my resistance is just 1 ohm. This may not be intuitive, give some specific examples. Common small pieces of metal, such as stainless steel spoons, screws, metal pots, etc., have a resistance of only a few tenths of a ohm. The resistance of the human body surface is about thousands of Euros to several hundred thousand Euros. This is related to the position, distance, degree of drying, and degree of delicateness of the skin. The surface resistance of beautiful women is often much smaller than that of rough men, because they have tender skin and plenty of water. So you can design an instrument that judges whether it is a beautiful woman based on this principle, give it to your girlfriend, and guarantee that she will like it very much. Probably it will scream because of this, and the cry is of course "Euro". The internal resistance of the human body is only a few hundred ohms to several thousand ohms. This is related to the site of measurement, the structure of different people (for example, the resistance of a person with more fat will be larger), moisture, salt, and even volume. relationship. Therefore, the measurement of human resistance can reflect many conditions of the body and can even be used to diagnose some lesions. Ohm's law is formulated as I=U/R. Where I is the current flowing through my body, U is the voltage across my end, and R is my resistance. Although it looks like this formula is simple, he is very useful. When you know any two of them, you can calculate another value. Using this formula, you can use voltammetry to measure my resistance. As long as the voltage U applied to me and the current I flowing through my body are measured, I can calculate that the resistance is R=U/I. In addition, when you know the current flowing through my body and my resistance, you can calculate the voltage across my end, that is, U=R*I. One thing to keep in mind is that in most cases, there is resistance in the conductor. Therefore, as long as there is current flowing through the conductor, there must be a voltage across the conductor. This is true even for Power Supply wires. Therefore, when conducting with a wire, it is important to notice the effect of the voltage drop due to the resistance of the wire on the circuit. There is also a resistance inside the power brother, which is called the internal resistance of the power supply. One of the reasons is that the power of the big brother in his body needs the conductor to help export it. Since it is a conductor, there must be resistance. Therefore, when the power is supplied to the outside, a voltage drop will occur in the internal resistance of the power supply, resulting in a decrease in the actual output voltage of the power supply. According to the formula U=R*I, it can be concluded that the greater the output current, the greater the voltage drop across the internal resistance. The voltage that the power supply itself can provide is fixed, so the greater the voltage drop across the internal resistance, the lower the external output voltage. From this point of view, the resistance is indeed a nuisance, where the power of the big brother could not be said. When referring to current and voltage, one has to mention electrical power P. I am very envious of the capacitor brothers and can always hide the positive and negative charges of the sisters in my heart. Although I have a lot of charge in my body, I don't think it is mine. They are only passers-by. When the positive and negative charges flow through us, either or both of the sisters' flowers, it always causes me to get hot. People call this phenomenon the thermal effect of current. The heat generated by the current per unit time on the resistor can be expressed by the formula P=I*I*R. Since U=I*R, this formula can also be written as P=I*U. Therefore, when the current is greater, the hotter heat of my body becomes stronger, and this heat is proportional to the square of the current. When the fever is too severe, I will not be able to tolerate it. There will be a series of symptoms such as smoking, burning, resistance, and even burning. So, dear electricians, please be sure to pay attention to the electric power we can afford. For a resistor, there is usually a nominal power value. This value indicates the maximum power that we can afford to work long-term under normal conditions. It is also not a bad thing for the resistance to flow through the electric current to generate heat. For example, the electric wire and rice cookers are all working by using the resistance wire to flow the electric current to generate heat. Normally, I should be a device with only two terminals. People are strange animals and they always abstract something. So people abstract our resistance into symbols. In the various circuit diagrams, our abstract symbols often appear brightly. In order to get different resistances, sometimes people will use two resistors in series or in parallel, as shown in the figure. Resistor series circuit has two characteristics, one is that the current flowing through each resistor is the same (because the charge can not disappear out of thin air, it is impossible to emerge out of thin air, so if the current in the series circuit is not the same, then it must be There are places where electricity is leaking, which means there are other slip roads. Think about the model of the water pipe. Two water pipes are connected in series. The flow of water flowing inside must be equal, otherwise there will be places where water leaks.) The second is that the total voltage of the circuit is equal to the sum of the voltages on these two resistors. Therefore, when the two resistors R1 and R2 are connected in series, the total voltage drop is U=I*R1+I*R2, which is U=I*(R1+R2). This calculation, when we are connected in series, the total resistance is the sum of the resistance of the two resistors. Similarly, resistance parallel circuits have two characteristics. One is that the voltages across the two resistors are equal. The second is that the total current of the circuit is equal to the sum of these two resistance currents (think about the model of the water pipe again. The output of the two pipes equals the output of the two pipes). Therefore, when the two resistors R1 and R2 are connected in parallel, the total current flowing through the circuit is I=U/R1+U/R2. To simplify, I=U*(1/R1 + 1/R2). That is, the total resistance of the parallel circuit is equal to the reciprocal of the sum of the reciprocals of the resistors. Guangzhou Lufeng Electronic Technology Co. , Ltd. , https://www.lufengelectronics.com
