The skin effect of LED basics
When you do LED testing, you should find that when you use a high-frequency current driver, it often appears black, which eventually leads to a dead light. Specifically, the colloid around the gold wire is carbonized and burnt black due to continuous high temperature. This is because the impedance at high frequency is much higher than the DC impedance, and the increase in impedance makes the gold wire heat more serious, causing the colloid to burn black, which causes this phenomenon. It is the skin effect.led bulb light
First, what is the skin effect
The skin effect is also called the skin effect. When the alternating current passes through the conductor, the current will concentrate on the surface of the conductor. This phenomenon is called the skin effect. The skin effect is a term for electromagnetism and eddy current (vortex current). This phenomenon is caused by energized ferromagnetic material, close to the unenergized ferromagnetic material, which produces a magnetic field in the opposite direction on the surface of the unenergized ferromagnetic material. When a magnetic field is generated, a current that cuts the magnetic field line is generated. This current is called a vortex. Current, this phenomenon is the skin effect.
Second, the principle of skin effect
The skin effect is that current or voltage is concentrated in the conductor surface when the higher frequency electrons are conducted in the conductor, rather than being evenly distributed across the cross-sectional area of the entire conductor. The skin effect increases the effective resistance of the conductor. The higher the frequency, the more pronounced the skin effect. When a very high frequency current is passed through the wire, it can be considered that the current flows only in a thin layer on the surface of the wire, which is equivalent to a reduction in the cross section of the wire and an increase in electrical resistance. Since there is almost no current flowing through the center portion of the wire, this center portion can be removed to save material. Therefore, a hollow wire can be used instead of a solid wire in a high frequency circuit. In addition, in order to weaken the skin effect, in the high-frequency circuit, a plurality of mutually insulated thin wires are often used to sew into a bundle instead of the thick wire of the same cross-sectional area, and the multi-strand wire harness is called a twisted wire.led tube light
Third, the application of skin effect
The intensity of the alternating electromagnetic field in the conductor decreases exponentially with the depth of the incoming conductor. Therefore, by incorporating conductive particles (usually zinc oxide and titanium oxide) into the sunscreen, the intensity of ultraviolet rays (high-frequency electromagnetic waves) in the sunlight can be made. reduce. This is one of the principles of physical sun protection. In addition, the skin effect is also one of the methods of electromagnetic shielding. The skin effect can prevent high-frequency electromagnetic waves from penetrating into a good conductor and forming an electromagnetic shielding device, which is also the reason why the mobile phone receives poor communication in the elevator. In industrial applications, the skin can be surface hardened using the skin effect.led ceiling light
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