Multilayer inductors are made of alternating layers of ferrite or ceramic and coil patterns. The coil pattern is not made by winding conductors, but by screen-printing conductors on top of the ferrite or other material. Layers and layers of this are used to give it the properties of a coil. On the other hand, due to its structure, it also has a capacitor component inside. Inductors are used in a variety of places in our daily lives.
Depending on the application, they are called coils, choke, reactor, solenoids, line filters, etc. The following is a list of typical names. An inductor mainly used in power supply circuits is called a choke coil. It is used to adjust AC current to unidirectional current and to remove noise. A common mode filter is characterized by the shape of two choke coils integrated together, and is used to remove noise in digital interfaces such as USB and HDMI. A coil with a donut-shaped ferromagnetic core is called a toroidal coil.
Unlike coils with rod-shaped cores, the magnetic flux in the winding leaks less to the outside. It is therefore highly stable and reproducible, and is often used in high-frequency circuits.
Date: Figure 1. Figure 2. Figure 3. Relevant technical knowledge What is the role of a Capacitor in Electronic Components? Focusing on the mechanism How diodes work and what they are used for! What kind of situations are they used in?
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Fig 6. The resistance present in the wire of large inductors has a noticeable effect on current through, and voltage across an inductor. Although the effect of reactance can be calculated, it will not account for the total effect on current and voltage, the resistance must also be taken into account.
The internal resistance of an inductor cannot be physically separated from the inductor as shown in Fig 6. Because V L is the phasor sum of the voltages V XL and V r due to both the reactance and the internal resistance of the inductor , it will also be slightly larger than the voltage V XL that would be calculated due to the inductance alone. Whilst this is not a big problem with the small inductors used in high frequency applications, it does need to be considered in large, low frequency inductors where the coil has many more turns an therefore its internal resistance is greater.
Hons All rights reserved. Revision Learn about Electronics - AC Theory. AC Theory Modules 2. Between points c and d, the current drops to zero as the voltage rises to its peak, and the process starts to repeat. Throughout the cycle, the voltage follows what the current is doing by one-fourth of a cycle:.
The capacitor is affecting the current, having the ability to stop it altogether when fully charged. Since an AC voltage is applied, there is an rms current, but it is limited by the capacitor. X C has units of ohms verification left as an exercise for the reader. X C is inversely proportional to the capacitance C ; the larger the capacitor, the greater the charge it can store and the greater the current that can flow. It is also inversely proportional to the frequency f ; the greater the frequency, the less time there is to fully charge the capacitor, and so it impedes current less.
The capacitor reacts very differently at the two different frequencies, and in exactly the opposite way an inductor reacts.
At the higher frequency, its reactance is small and the current is large. Capacitors favor change, whereas inductors oppose change. Capacitors impede low frequencies the most, since low frequency allows them time to become charged and stop the current.
Capacitors can be used to filter out low frequencies. For example, a capacitor in series with a sound reproduction system rids it of the 60 Hz hum. Although a capacitor is basically an open circuit, there is an rms current in a circuit with an AC voltage applied to a capacitor.
This is because the voltage is continually reversing, charging and discharging the capacitor. If the frequency goes to zero DC , X C tends to infinity, and the current is zero once the capacitor is charged. Capacitors have the opposite effect on AC circuits that inductors have. Just as a reminder, consider Figure 3, which shows an AC voltage applied to a resistor and a graph of voltage and current versus time.
The voltage and current are exactly in phase in a resistor. There is no frequency dependence to the behavior of plain resistance in a circuit:. Figure 3. Inductive reactance X L has units of ohms and is greatest at high frequencies. X C has units of ohms and is greatest at low frequencies. Conceptual Questions 1. Presbycusis is a hearing loss due to age that progressively affects higher frequencies.
A hearing aid amplifier is designed to amplify all frequencies equally. Would you use a large inductance or a large capacitance in series with a system to filter out low frequencies, such as the Hz hum in a sound system?
High-frequency noise in AC power can damage computers. Does the plug-in unit designed to prevent this damage use a large inductance or a large capacitance in series with the computer to filter out such high frequencies?
Explain why the capacitor in Figure 4 a acts as a low-frequency filter between the two circuits, whereas that in Figure 4 b acts as a high-frequency filter. Figure 4. Capacitors and inductors. Capacitor with high frequency and low frequency.
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