How does resistance work? The principle and function of resistors

Definition: The resistance of a conductor to an electric current is called the resistance of a conductor. Resistors are the most used components of all electronic circuits.

The main physical characteristic of the resistor is that it transforms electrical energy into thermal energy, which can also be said to be an energy-dissipating element, and the internal energy is generated when the current passes through it. Resistors usually play the role of voltage divider shunt in circuits, and for signals, both AC and DC signals can pass through resistors. Resistors all have a certain resistance value, which represents the amount of resistance to the current flow.

The unit of resistance is ohms, which is denoted by the symbol " ". The ohm is defined as follows: when a voltage of 1 volt is applied to both ends of a resistor, if 1 ampere of current passes through the resistor, the resistance of the resistor is 1 ohm.

In addition to ohms, the units of resistance include kiloohms (k), megaohms (m), etc.

And that's what you're asking, and it's not just about molecules, it's about atoms.

The valency of metals is generally positive, take aluminum and copper as an example, aluminum has three free electrons in the outermost shell, but the electrons are very close to the nucleus, and the attraction is stronger than copper's attraction to its own electrons, so the electrons of aluminum are not as free as copper, and the conductivity is not as good as copper, and what does it depend on these free electrons, they are equivalent to highways, because the electrons are attracted to the nucleus, if you don't give me an electron, I won't let go of my original electrons, so the metal itself will not discharge, but it will conduct electricity when it is electrified.

Insulating materials are generally macromolecules, such as rubber, plastic, and a lot of elements are put together, so that there aren't too many very free electrons, and they're all tightly bound, which means that the outermost electrons are eight, and this stable structure, of course, is common to some of them, and you can learn about organic chemistry.

Generally speaking, it is easy to judge the quality of the resistance by using a multimeter: adjust the multimeter to the appropriate position of the resistor, and place the two meter pens of the multimeter on both ends of the resistor, and the resistance value of the resistance can be read from the multimeter. It should be noted that the hand should not touch the metal part of the pen when testing the resistance.

However, in actual appliance repairs, resistor damage rarely occurs. It is important to pay attention to whether the resistor is soldered or desoldered.

Function: The main function is to hinder the flow of current, which is used for current limiting, shunting, step-down, voltage division, load and capacitor with cooperative filters and resistance matching. There are pull-up resistors and pull-down resistors in digital circuits.

According to the ministerial standard (SJ-73), the naming of resistors and potentiometers consists of the following four parts: the first part (main name); Part II: (Materials); Part III (Taxonomic Characteristics); Part IV (Serial number). Their models and meanings are shown in the table below.

Parallel equivalent resistance.

In the circuit where the resistors are connected in parallel, the applied voltage at both ends has a total current of i, and the currents of each branch are i1 and i2 respectivelyin.

According to the KCL rule, i=i1+i2+.in=u/r

r is the total resistance of the parallel circuit, which is called the parallel equivalent resistance.

Equivalent resistance in series.

A circuit in which resistors are connected in series, with an external voltage applied at both ends, and the same current flows through each resistor.

According to the KVL law, the total resistance of the series resistance is called the series equivalent resistance.

In circuit calculations, it is necessary to grasp the principle of equal currents.

The principle and function of the resistor are as follows:

The role of resistance.

1. Current limiting: The meaning of current limiting is to limit the current, and the role in the circuit is mainly to prevent damage to other components due to excessive current, so the resistance in series in the circuit at this moment mainly plays a role in protecting the normal operation of other components.

2. Shunt: Shunt mainly refers to the resistor being connected in parallel on the components or corresponding circuits that need to be shunted, so as to separate the excess current, but the voltage is inconvenient.

3. Voltage division: Voltage division refers to the resistance in the form of a series circuit for voltage division, and the general voltage divider resistor will be more famous for the demand characteristics of the buried circuit to select different resistance values and power resistance.

4. Heating: Our daily electrical equipment, such as induction cookers and heaters, is the principle that when an electric current passes through the resistance, it will convert electrical energy into heat energy, so as to make the resistance heat.

In addition to the role of voltage limiting shunt, the resistor can also be used as a matching load in the circuit. According to the requirements of different circuits, it can also be used for feedback of amplification circuits, voltage-current conversion, voltage or current protection components in the event of input overload, and RC oscillation circuits.

How the resistor works.

Resistance is a physical quantity that in physics indicates the magnitude of a conductor's action on the resistance of an electric current. When the resistance of the conductor is greater, it means that the conductor has a greater blocking effect on the current, and the current flowing through the conductor is smaller, and vice versa.

Different conductors, the resistance is generally different, and resistance is a property of the conductor itself. The resistance of a conductor is usually represented by the letter r, and the unit of resistance is ohms, or ohms for short. The main physical characteristic of resistance is the conversion of electrical energy into thermal energy, and the internal energy is generated when an electric current passes through it.

The magnitude of the resistance value of a resistive element is generally related to temperature, material, length, and cross-sectional area.

Classification of resistors:

1. According to the characteristics of the resistance value, it can be divided into: fixed resistance, adjustable resistance, special resistance (sensitive resistance).

2. According to the manufacturing materials, it can be divided into: carbon film electro-hydraulic car resistance, metal film resistance, wirewound resistance, non-inductive resistance, thin film resistance, etc.

3. According to the package form, it can be divided into: chip resistance and in-line resistance.

Resistors usually play the role of voltage division and shunt in circuits. Working principle: The resistor is composed of three parts: the resistor body, the skeleton and the outlet of the lead state, and it is only the resistor that determines the resistance value.

In order to ensure the normal operation of the electrical appliance, a variable resistor can usually be connected in series in the circuit in order to ensure the normal operation of the electrical appliance.

The role of resistance in a circuit.

1. Current limiting. In order to ensure the normal operation of the electrical appliance, a variable resistor can usually be connected in series in the circuit in order to ensure the normal operation of the electrical appliance. When the magnitude of this resistance is changed, the magnitude of the current also changes.

We call this resistor, which can limit the amount of current, a current-limiting resistor.

2. Diversion. When several electrical appliances with different rated currents need to be connected at the same time on the main circuit of the circuit, a resistor can be connected in parallel at both ends of the electrical appliances with smaller rated current, and the function of this resistor is to "shunt".

3. Partial pressure. If the power supply is higher than the rated voltage of the electrical appliance, the electrical appliance should not be directly connected to the power supply. In this case, a resistor with a suitable resistance value can be connected in series to the electrical appliance, so that it can share a part of the voltage, and the electrical appliance can work under the rated voltage and voltage.

We call such resistors voltage-dividing resistors.

4. Convert electrical energy into internal energy.

When an electric current passes through a resistor, it converts all or part of the electrical energy into internal energy. The electrical appliances used to convert electrical energy into internal energy are called electrical appliances.

How resistors work.

In physics, resistance is used to express the magnitude of a conductor's resistance to an electric current. The greater the resistance of a conductor, the greater the resistance of the conductor to the current. The resistance of different conductors is generally different, and resistance is a characteristic of the conductor itself.

A resistive element is an energy-dissipating element that hinders the current current. Because of the hindrance effect of the substance on the electric current, it is called the resistive substance under the action.

The resistance will cause a change in the flow of electrons, the smaller the resistance, the greater the flow of electrons, and vice versa. The resistance value of the resistive element is generally related to the temperature, material, length, and cross-sectional area, and the physical temperature coefficient of the resistance affected by the temperature in the balance branch source is the temperature coefficient, which is defined as the percentage of the change in the resistance value for every 1 increase in temperature.

An introduction to resistors

Resistance is the ability in a substance to hinder the flow of electrons, i.e., the value of resistance, in units. A resistor is a device that has a certain resistance to the flow of current. For the sake of convenience, resistors are often referred to simply as resistors.

1. Principle: The resistor is composed of three parts: the resistor, the skeleton and the lead-out end (the resistor and the skeleton of the solid core resistor are combined into one), and only the resistor determines the resistance. Usually, the resistance is defined according to Ohm's law, and how much current will be generated if a constant voltage is added to the resistance; Alternatively, Joule's law defines how much heat is generated per unit of time when a resistor flows through an electric current.

2. Current limiting: Sometimes a group of tens of milliamperes of power supply is needed in the circuit, but its voltage is not used elsewhere in the circuit, and it is not suitable to make a group of DCDC or LDO alone, because the current is too small. In this case, a regulator tube regulator circuit can be used.

3. Voltage division: voltage division, such as ADC sampling circuit, DCDC output voltage feedback, level translation, etc.