What does it mean that resistance is proportional to temperature

1.In general, the resistance increases with increasing temperature.

2.There are some special resistance materials, the resistance increases linearly with temperature, that is, the functional relationship between resistance and temperature is a primary function (linear function), and the resistance-temperature image drawn is a straight line.

3.The fact that resistance is proportional to temperature means that the function of resistance to temperature is proportional (a special primary function), and the resulting resistance-temperature image is a straight line through the origin.

This situation is generally not present because it is necessary for the resistance to be zero when the temperature is zero.

Only superconducting materials are possible.

4.Because it can be said clearly, there is no need for analogy. Either it would be self-defeating.

Reflection: The reason for the misdirection is that some people say that the relationship between the increase function is proportional.

Generally, metal materials have a positive temperature coefficient, that is, the resistance of the conductor increases with the increase of temperature, that is, the resistance is proportional to the temperature.

Platinum RTD, copper RTD, tungsten wire for electric lamps, and furnace wire for electric furnaces are all proportional.

Generally, non-metals have a negative temperature coefficient, and the temperature increases, and the resistance decreases, which is inversely proportional.

FYI.

The resistance of the resistor increases with increasing temperature.

The proportional relationship is reflected in the image as an oblique straight line that crosses the origin.

Build a plane Cartesian coordinate system, the horizontal axis represents the resistance value, the ordinate represents the temperature, and then draw an oblique straight line through the origin.

It is possible to read the resistance value of the resistance at different temperatures.

When metallic, the higher the temperature, the greater the resistance.

Reason: Metals are conductive because they have freely moving electrons (irregular) inside them. When the temperature rises, these electrons vibrate back and forth so intensively that they hinder the current.

The higher the temperature of non-metallic substances (some semiconductors), the lower the resistance. Reason: When the temperature rises, the internal electronic movement intensifies (but does not vibrate back and forth), which in turn can carry an electric charge.

For example, the resistance of a metal always increases with the increase in temperature, because the heat movement of the molecules in the metal is due to the difficulty of the temperature increase.

The result of exacerbation. When the resistance of the conductor is 1, the temperature changes by 1, and the value of the resistance change is called the temperature coefficient of resistance.

The temperature coefficient of resistance of constantan and manganese copper is very small, and its resistance is almost not affected by temperature, so it is commonly used to manufacture standard resistors or rheostats.

Some substances (e.g., electrolytes.

When the temperature rises, due to positive and negative ions.

As the motion accelerates, the resistance decreases, and the temperature coefficient of resistance is negative.

The resistance of metals always increases with the increase of temperature and noise, and non-metallic substances (some semiconductors orElectrolyteThe higher the temperature, the lower the resistance.

In the case of a metal conductor, there are a large number of free electrons inside it at room temperature.

The temperature does not have much effect on the number of free electrons. The higher the temperature, the more intense the thermal motion of the metal atoms will be, and the greater the obstruction effect on the directional motion of free electrons. Therefore, for metal conductors, the higher the temperature, the greater the resistance.

But in general, this change is very small, and people tend to ignore it. But sometimes this change is very obvious, for example: an incandescent light bulb of tens of watts has a resistance of only a few tens of ohms at room temperature, but the resistance reaches when it is working normally.

1. Two thousand ohms.

For some insulating materials and semiconductor materials.

The main factor that affects the magnitude of their resistance is the number of movable charged particles, and the temperature can greatly increase these particles. Therefore, temperature has a very large influence on the conductivity of these materials. Some insulators.

This is why most semiconductor materials become conductors at high temperatures, and the resistance of most semiconductor materials decreases rapidly when the temperature rises.

Reasons why temperature affects resistance:

Temperature is the thermal motion of molecules.

is a sign of the frequency (referred to as the peak frequency) of the peak radiant intensity generated, rather than the average kinetic energy of the thermal motion of the molecule. The reason for the modification of the definition of temperature is that most substances will absorb or release a large amount of heat without starvation during the phase change, so it cannot be said that temperature is a sign of the average kinetic energy of molecular thermal motion!

For most conductors, the higher the temperature, the greater the resistance, such as metals.

For 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 factors such as whether the conductor is connected to the circuit, whether there is electricity in the conductor, and the magnitude of the current.

Resistance. The resistance of the conductor to the current is called the resistance of the conductor. Resistance (usually denoted by "r") is a physical quantity.

In physics, it is expressed as the magnitude of the effect of a conductor on the resistance of an electric current. 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 the electrical dissipation resistance is a property of the conductor itself. The resistance of a conductor is usually denoted by the letter r, and the unit of resistance is ohms.

Abbreviated as Europe, the symbol is .

The unit of resistance.

The unit of resistance is the ohm, referred to as ohm, in the Greek alphabet.

Denote. The commonly used units of resistance are kiloohms (k) and megaohms (m), and their relationship is: 1k 1000, 1m 1000k.

The temperature precedent expresses the average kinetic energy of the atoms in the object. That is, the higher the temperature of the object, the faster the atoms will be and the less resistance there will be.

Details:

Although resistance is defined as: 1 volt voltage produces one ampere of current is 1 ohm resistance; However, voltage and current are not the factors that determine resistance.

The resistance value of the resistive element is generally related to the temperature, but also to the conductor length, cross-sectional area, and material Douhui. While the resistance of most (metals) increases with temperature, the opposite is true for some semiconductors.

For example, in glass, carbon has the formula r = l s at a certain temperature, where is the resistivity.

l is the length of the material, the unit is m, s is the area, and the unit is square meters. It can be seen that the resistance of the material is proportional to the magnitude of the resistance.

inversely proportional to the length of the material.

in its area.

We know that all conductors have the property of hindering the current current, and this property is called resistance. We also know that the resistance of a conductor is a property of the conductor itself, and its size is determined by the length, cross-sectional area, and material of the conductor.

When we measured the resistance of the conductor with a voltmeter and an ampere meter, we found that if the DUT was a small bulb, then when different voltages were taken at both ends of the bulb, the measured resistance values were also different, which exceeded the allowable range of error. Why is that? To figure this out, let's take a look at two small experiments.

Experiment 1: connect the filament of a damaged fluorescent lamp in series with a small bulb, connect it into the circuit, turn on the power supply to make the small bulb glow normally, burn the filament of the fluorescent lamp with a match, you will find that the small bulb is obviously dimmed, move the firewood, and the small bulb will return to normal light.

Experiment 2: Replace the fluorescent filament in experiment 1 with a nickel-chromium alloy, and repeat the above experimental process, we will find that there is no obvious change in the brightness of the small bulb.

In experiment 1, the small bulb became darker because the temperature of the filament of the fluorescent lamp increased and the resistance increased, resulting in a decrease in the power allocated by the small bulb. The temperature of the nichrome wire in experiment 2 also increased, but the brightness of the small bulb did not change significantly, so it must have been that the resistance of the nichrome wire did not change significantly. It can be seen that the resistance of a conductor is related to temperature, and the resistance of conductors of different materials is affected by temperature differently.

When the temperature changes, the resistivity of the material, the length and cross-sectional area of the conductor all change, and most pure metals change when the temperature changes 1, the resistivity changes, and the length of the conductor generally only changes. Therefore, when considering the change in the resistance of a metal conductor with temperature, we can ignore the change in conductor length and cross-sectional area. That is, the change in resistance with temperature is due to the change in resistivity with temperature.

The resistivity of pure metals varies with temperature relatively regularly, and when the temperature change range is not large, there is an approximate relationship between resistance and temperature as follows.

ρ0(1+at)

where the resistivity at t is denoted and 0 is the resistivity at 0, which is called the temperature coefficient of resistance, and the unit is 1 degree, and the temperature coefficient of resistance is different for different materials. Some alloys have a particularly small temperature coefficient of resistance, so the resistance wound with these alloy wires is very little affected by temperature and is often used as a standard resistor.

The relation between resistance and temperature t( ) is t= 0(1+at), where t and 0 are the resistivity at t and 0, respectively.

After knowing the law that the value of the material changes with temperature, a resistance thermometer can be made to measure the temperature. Semiconductor materials are generally negative and have large values. The made resistance thermometer has a high sensitivity.

Some metals (such as Nb and Pb) or their compounds, when the temperature drops to a few K or more than a dozen K (absolute temperature), suddenly decreases to close to zero, and superconductivity occurs.

1.Metal conductors: Well, for most metal conductors, there is a special relationship with temperature.

When the temperature rises, the resistance value increases like a roast. Why the Hidden Woods? Well, it's not easy.

We can explain it with the theory of free electrons. At low temperatures, the free electrons in the metal are struck by ions in the crystal lattice, resulting in the generation of electrical resistance. However, when the temperature rises, the ions begin to "dance", the collision between electrons and ions increases, and the resistance value increases!

2.Semiconductor Materials: Well, the relationship between the resistance and temperature of semiconductors is a bit complicated.

It depends on the type and concentration of impurities. In some semiconductor materials, if the concentration of impurities is low, the resistance will decrease with the increase of temperature, which is called a negative temperature coefficient. In some semiconductors, if the concentration of impurities is high, the resistance will rise along with the temperature, which is called a positive temperature coefficient.

It's like a symphony, impurities determine the direction of the notes, and temperature is the master conductor of the symphony. It's a bit mysterious, right?

3.Thermistor: Haha, that's an extraordinary guy!

The thermistor is the only resistor used to sense the temperature in the town. It is generally made of metal oxides, and its resistance value will be linear with temperature. As the temperature rises, the resistance value increases, just as everyone sees less money in their wallets.

They are very important elements and can be found in places like thermometers and heating controllers in your home.

In short, the relationship between temperature and resistance is varied, and various materials have various patterns. Metal conductors, semiconductor materials, and thermistors all have their own"Tricks"It is necessary to understand the intimate relationship between them through different theories and experiments. Hey, these relationships are extremely useful and important in the fields of electronics, industrial control, and sensing technology.