What is Resistor? What is Resistance?

Resistance. 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 " ". Ohm is defined like this:

When a voltage of 1 volt is applied to both ends of a resistor, if 1 ampere of current passes through the resistor, the resistor has a resistance of 1 ohm. In addition to ohms, the units of resistance include kiloohms (k), megaohms (m), etc.

The electrical performance indicators of resistors usually include nominal resistance, error and rated power.

Together with other components, it forms some functional circuits, such as RC circuits.

A resistor is a linear element. It is said to be a linear element because it has been experimentally found that under certain conditions, the current flowing through a resistor is proportional to the voltage across the resistor – that is, it conforms to Ohm's law: i = u r

Common carbon or metal film resistors can be simulated with linear resistors when the temperature is constant and the voltage and current values are limited to the specified conditions. If the voltage or current value exceeds the specified value, the resistor will overheat and will not obey Ohm's law and may even burn out. The relationship between the operating voltage and current of a linear resistor is shown in Figure 1.

There are many types of resistors, usually divided into carbon film resistors, metal resistors, wirewound resistors, etc.: it includes fixed resistors and variable resistors, photoresistors, varistors, thermistors, etc. But no matter what kind of resistor it is, it has a basic representation of the letter "r".

The unit of resistance is expressed in ohms ( ). What does it include? (ohms), k (kiloohms), m (megaohms). The conversion relationship is:

1mω=1000kω ，1kω=1000ω。

The resistance value standard method of resistor usually has the color ring method and the number method. The color ring method is more common in general resistors. Since the resistance in the mobile phone circuit is generally relatively small, it is rarely marked with a resistance value, and even if there is, the digital method is generally used, namely:

101 - represents the resistance of 100; 102 – represents the resistance of 1k; 103 – represents a resistance of 10k; 104 – represents a resistance of 100k; 105 - represents the resistance of 1m; 106 – indicates a resistance of 10m.

What is the concept of resistance.

The resistance of a conductor to the current passing through the conductor is called the resistance of the conductor.

The resistance of a conductor to an electric current is called the resistance of a conductor.

The so-called resistance is also the resistance of electricity.

Resistant, obstructive, obstructive, obstructive also. Everything in the world can be called.

The current is blocked and this blocking substance is also known as resistance.

Something that usually plays a current-limiting role in an electrical circuit.

Resistance, denoted by the symbol r. At its most basic, it is to block the flow of electric current. The two most basic parameters to measure a resistor are resistance and power.

The resistance value is used to indicate the magnitude of the resistor's effect on the current resistance, and is expressed in ohms. In addition to the basic units, there are kiloohms and megaohms. Power is used to indicate the maximum current that the resistor can withstand, expressed in watts, there are 1 16W, 1 8W, 1 4W, 1 2W, 1W, 2W, etc., beyond this maximum, the resistor will burn out.

According to the different materials of resistors, there are cement resistors (low production cost, high power, high thermal noise, inaccurate resistance value, unstable work), carbon film resistors, metal film resistors (small size, stable work, low noise, high precision) and metal oxide film resistors and so on. According to whether its resistance value is variable or not, it can be divided into trimmer resistor, adjustable resistor (potentiometer), etc.

Resistance unit conversion: 1k = 1000, 1m = 1000k.

The greater the resistance of a conductor, the greater the resistance of the conductor to the current. 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 ohm, or short as .

When the voltage at both ends of the conductor is constant, the greater the resistance, the smaller the current passing through; Conversely, the smaller the resistance, the greater the current that will pass through. Therefore, the magnitude of the resistance can be used to measure the strength of the conductor's resistance to the current, that is, the conductivity is good or bad. The amount of resistance is related to factors such as the material, shape, and volume of the conductor, as well as the surrounding environment.

Extended Materials. The electric current in a metallic conductor is formed by the directional movement of free electrons. Free electrons collide frequently with metal cations in motion, and the number of collisions per second is as high as about 1015.

This collision hinders the directional movement of free electrons, and the physical quantity that indicates this hindrance is called resistance. Not only metal conductors have resistance, but other objects also have resistance.

Influencing factors: 1. Length: When the material and cross-sectional area are the same, the longer the length of the conductor, the greater the resistance.

2. Cross-sectional area: When the material and length are the same, the smaller the cross-sectional area of the conductor, the greater the resistance.

3. Material: When the length and cross-sectional area are the same, the conductor resistance of different materials is different.

4. Temperature: For most conductors, the higher the temperature, the greater the resistance, such as metalsFor a few conductors, the higher the temperature, the lower the resistance, such as carbon.

Resistance is a property of the conductor itself, so the resistance of the conductor has nothing to do with whether the conductor is connected to the circuit, whether there is current in the conductor, the magnitude of the current, and other factors. The resistivity of a superconductor is zero, so the resistance of a superconductor is zero.

1. Current limiting: In order to make the current through the electrical appliance not exceed the rated value or specified value required for actual work, so as to ensure the normal operation of the electrical appliance, a variable resistor can usually be connected in series in the circuit. When the magnitude of the resistance changes, so does the current ridge.

We refer to this resistor that can limit the current as current-limiting.

2. Shunt: When it is necessary to connect several loads with different rated currents to the main circuit at the same time, a resistor can be connected in parallel at both ends of the load with lower rated current, and the function of the resistor is shunt.

3. Voltage division: Usually, the rated voltage is marked on the electrical appliance. If the power supply is higher than the rated voltage of the appliance, it is not allowed to connect the appliance directly to the power supply.

In this case, the appliance can be connected in series with a resistor with an appropriate resistance value to share part of the voltage, and the appliance can operate at the rated voltage. We call this resistor a voltage divider.

4. Convert electrical energy into internal energy: When the current passes through the resistor, it converts all (or partial) of the electrical energy into internal energy. The appliances used to convert electrical energy into internal energy are called electric heaters, such as electric soldering irons, electric stoves, electric cookers, heaters, etc.

One of the most important aspects to consider during use is the length: when the material and the cross-sectional area of the traverse brigade are the same, the longer the length of the conductor, the greater the resistance.

Specifically, we can also mention the cross-sectional area of the resistor: the smaller the cross-sectional area of the conductor, the greater the resistance when the material and length are the same. Different materials are selected in the process of using resistors.

Material: When the length and cross-sectional area are the same, the conductor resistance of different materials is different.

In order to ensure that the electrical current through the flushing electrical appliance does not exceed the rated or specified value required for the actual number of working limbs, and to ensure the normal operation of the electrical appliance, a variable resistor can usually be connected in series in the circuit. When the magnitude of the resistance changes, the current also changes. We refer to this resistor that can limit the current as current-limiting.

The English name of resistance is resistance, usually abbreviated as R, it is a basic property of conductors, which is related to the size, material, and temperature of the conductor. Ohm's law states that the relationship between voltage, current, and resistance is i=u r, i.e., r=u i. The basic unit of resistance is the ohm, which is represented by the Greek letter " ".

When an electric current passes through a conductor, the conductor has a certain obstruction effect on it, and people call this hindrance the resistance of the conductor.

Scientists have measured through precise experiments that the resistance of a conductor is proportional to the length of the conductor, inversely proportional to the cross-sectional area of the conductor, and related to the material of the conductor. This law is called the Law of Resistance.

Conductors made of different materials have different levels of resistance. For example, the resistance of copper wire is smaller, the resistance of aluminum wire is slightly larger, and the resistance of iron wire is greater.

The resistance of a conductor to an electric current is called the resistance of the conductor.

Resistors, abbreviated as resistors (usually denoted by masking "R"), are the most widely used components in all electronic circuits. The main physical characteristic of the resistor is that the substation macro spring energy is thermal energy, which can also be said to be an energy-dissipating element, and the current passes through it to generate internal energy. Resistors usually play the role of voltage divider shunt in the circuit, and for Xinsen cavity, both AC and DC signals can pass through the resistor.