What is Ohm's Law?
Ohm's Law is the most fundamental law expressing the relationship between the voltage, current, and resistance in a direct current circuit.
This law mathematically expresses the relationship that "the current is proportional to the voltage and inversely proportional to the resistance". So the law is essential when calculating the current flowing in a circuit or when seeking the required value for the resistance.
Voltage (V) = Resistance (R) × Current (I)
- Voltage (V) [Unit: V]: the force that pushes the electrons
- Current (I) [Unit: A]: the quantity of electrons flowing
- Resistance (R) [Unit: Ω]: the degree to which the flow of electrons is hindered
What is impedance?
Impedance is the concept that extends Ohm's Law to alternating current circuits.
In an alternating current circuit, there are parts such as a coil (inductance, L) and a capacitor (capacitance, C) that change behavior according to the frequency, not the resistance (R).
Impedance (Z) performs the role of resistance in these alternating current circuits.
Because the value of the impedance varies depending on the frequency of the alternating current signal, the impedance is treated as a combination of the resistance (R), the coil (inductance), and the capacitor (capacitance).
Voltage (V) = Impedance (Z) × Current (I)
Impedance (Z) [Unit: Ω]: the degree to which the flow of the alternating current is hindered by all three of the resistance, coil, and capacitor combined
Two elements that make up the impedance
The impedance (Z) consists of a real number component, "the resistance (R)", and an imaginary number component, "the reactance (X)".
- Resistance (R) [Unit: Ω]: an element that hinders both a direct current component and an alternating current component
- Reactance (X) [Unit: Ω]: elements such as the coil and the capacitor that hinder the flow of the current depending on the frequency
In other words, impedance is the combination of the resistance (R) that does not depend on the frequency, and the reactance (X) that does depend on the frequency. This is extremely important when analyzing an alternating current circuit.
Joined Torex Semiconductor in 2005.
After six years engaged in the development of power ICs such as DC/DC converters, worked for three years providing technical support for offline LED drivers.
Later took charge of technical support for Torex’s power IC customers.
With expertise gained through product development and extensive know-how accumulated from years of customer support — including solutions for power-related issues and troubleshooting — currently engaged in providing technical support and product proposals for Torex products.