Why does the resistance of metal conductor increase with the increase of temperature?

Because in the directional drift motion, electrons are hindered by the collision between electrons in the metal and atoms in the lattice, the farther away the thermal vibration of atoms is from its regular position, the more chances it will collide with electrons, the greater the obstacle to electron drift, and the greater the resistance the conductor presents.

In metals and graphite, the nucleus and inner electrons form atomic reality and are regularly arranged in a lattice, while the valence electrons in the outer layer are easy to break away from the nucleus and become free electrons, which constitute conductive carriers.

The concentration of free electrons in metal and graphite is very large, about per cubic centimeter 1022, so the resistivity of metal and graphite is very small and the conductivity is very high. Generally, it decreases with the decrease of temperature. There is no chemical reaction between metal and graphite in the process of conducting electricity, and there is no significant material transfer.

Extended data

If external reasons are used, such as heating or irradiation with X-rays, γ-rays or ultraviolet rays, gas molecules can dissociate, so ionized gas becomes a conductor. The conductivity of ionized gas is closely related to the applied voltage, which is often accompanied by physical processes such as sound generation and light emission. Ionized gases are often used in the manufacturing of electric light sources.

The conduction of gas under the action of external ionization agent is called unconscious discharge of gas. As the applied voltage increases, the current also increases. When the voltage increases to a certain value, the non-self-sustaining discharge reaches saturation. When the voltage continues to increase to a certain value, the current suddenly increases sharply. At this time, even if the ionization agent is removed, it can still remain conductive, and the gas will transition from non-self-sustaining discharge to self-sustaining discharge.

The characteristics of gas self-sustaining discharge depend on many factors, such as gas type, gas pressure, electrode material, electrode shape, electrode temperature, electrode spacing and so on. Under different conditions, self-sustaining discharge has different forms, such as glow discharge, arc discharge and corona discharge.

Non-self-sustaining discharge and self-sustaining discharge of gases have many practical applications.

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