Control Panel Cooling units Technical Information
3-5. Electrical resistance basics
This section explains the electrical resistance and temperature
(1) Electrical resistance changes with temperature.
Environmental temperature change is extremely important for electrical property tests.
Electrical resistance changes with temperature.
In case of inspecting electrical characteristics for quality control, it is necessary to pay attention to temperature changes in the inspection environment.
This "temperature change in electrical resistance" varies depending on the conductor material (type of metal).
In this chapter, let's take a look at temperature control during the electrical property test along with checking the temperature change in electrical resistance.
(2) Electric current is the movement of charged particles (such as electrons) through a substance.
Ease or difficulty of particle movement depending on each substance is electrical resistance.
The Ohm (Ω) law
Electrical resistance is the resistance that occurs when an electric current flows.
Electric current flows when there is an electric potential difference between two points in an electric circuit.
Voltage is V, current is I, and resistance is R, V=IR…①
This is the Ohm (Ω) law.
"Electrical resistance" calculated by the particle stream
The phenomenon of electricity flows occur when charged particles (carriers) move due to an externally applied electric field.
These charged particles are the electron for metal conductors, the electron and electron hole for semiconductors, and the ion for an electrolyte.
Electrical resistance (R) is calculated by the formula "R=d/nqμS".
q indicates the electric charge of charge carriers flowing within the conductor of the uniform cross-sectional area S, n is the value per unit volume, and v is the average velocity.
The electric current I is the amount of charge passing through the cross-section of the conductors in one unit time.
v is proportional to the strength of the electric field E, if its proportionality is μ,
this μ indicates carriers' mobility in the substances.
The length of the object is d, and the voltage on both ends is V,
by ②, ③, ④
Therefore, by the formulas ①, ⑤,
Varies by substances "Electric resistivity"
In electrical resistance (R) = d/nqμS, when S = 1 [m2] and d = 1 [m], the value of electrical resistance is the resistivity of the material and is expressed as ρ [Ω・m].
While there are various electronic products and other technologies that make use of the fact that ρ differs depending on the material, it also creates various problems in terms of electrical characteristics.
Previous item: 3-4. Thermal expansion coefficient
Next item: 3-6. Relationship between electrical resistance and temperature
We're here to give you quick answers to your questions.