Understanding the Q-Factor of Inductors in Resonant Systems

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In summary, the Q-factor is a measure of how closely a real inductor behaves like an ideal inductor, with an infinite Q at all frequencies. However, due to losses from resistive wire, real inductors have a finite Q. This can be defined for an inductor alone when subjected to AC, as a measure of deviation from an ideal component.
  • #1
Dominique
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Hi all,

For a resonant system, there is usually a transfer of energy into another kind of energy back an forth (kinetic to potential; electric to magnetic, etc). for an LC tank or an RLC circuit, we know that the energy is transferred from as an electric field between the capacitor's plate to a magnetic field around an inductor coil.

But, how come we can define a q-factor for an inductor alone?

Thank you very much for your help :)
 
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  • #2
You can't.
The Q-factor is a measure of how closely a real inductor comes to behaving like an ideal inductor; an ideal inductor would have an infinite Q at all frequencies but real inductors are made from resistive wire etc so there are always losses.
 
  • #3
You can define a Q-factor for many situations where oscillation occurs.

Inductors, and capacitors have a Q when are subjected to AC. It sort of is a measure of deviation from an ideal component as said.
 
  • #4
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1. What is Q-factor of an inductor?

The Q-factor of an inductor is a measure of its quality or efficiency in storing and releasing energy. It is defined as the ratio of the reactance (resistance to change in current) to the resistance of the inductor. A higher Q-factor indicates a more efficient inductor.

2. Why is Q-factor important in inductors?

The Q-factor is important because it determines the bandwidth and selectivity of an inductor. A higher Q-factor means a narrower bandwidth and better selectivity, which is useful in applications such as filters and resonant circuits.

3. How is Q-factor calculated?

The Q-factor of an inductor can be calculated using the formula Q = XL/R, where XL is the inductive reactance and R is the resistance of the inductor. XL can be calculated using the formula XL = 2πfL, where f is the frequency and L is the inductance of the inductor.

4. What affects the Q-factor of an inductor?

The Q-factor of an inductor is affected by factors such as the inductor's physical construction, the material it is made of, and any external circuitry connected to it. It also decreases with increasing frequency due to the skin effect, which causes higher resistance at higher frequencies.

5. How can the Q-factor of an inductor be improved?

The Q-factor of an inductor can be improved by using high-quality materials with low resistance, reducing the number of turns in the coil, and minimizing any external circuitry that may affect the inductor's performance. Proper shielding and reducing the inductor's physical size can also help improve its Q-factor.

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