# Questions tagged [reactance]

The opposition of a circuit element to a change of electric current or voltage, as happens in capacitors and inductors.

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### What unit is expressing the effect of this capacitor in a common emitter amplifier?

I'm working through this handout I3.PDF in my attempt to understand negative feedback in amplifiers. The following formula appears, in which the author is substituting $v_{out}$ and $v_{in}$ to ...
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### Why does impedance decrease in an MLCC as frequency increases?

I understand that the impedance of any capacitor decreases as frequency reaches the resonance frequency, following the formula Xc = 1 / ( 2 pi f C ), but why does the impedance of an MLCC such a ...
793 views

### Why does wire not have large capacitive reactance?

For capacitive reactance, I am presented this formula: $$X_C = -\frac{1}{2\pi fC}$$ Where clearly, the capacitive reactance is inversely proportional to the capacitance. This confuses me. We usually ...
66 views

### How do you calculate phase shift induced by a shunt capacitor?

Given a simple loaded-line shunt-capacitor phase shifter, how can I calculate the phase shift and insertion loss at S21 caused by the shunt capacitor (varicap in my case, but for any cap) assuming I ...
2k views

### What is Negative Inductance?

I am experimenting with a stripline square spiral inductor in Sonnet and the graph is showing both a positive and negative inductance. What does it mean to have a negative inductance? Why does it ...
61 views

### Capacitive reactance related to frequency

Why does capacitive reactance decrease with the increase of the frequency of the applied signal? It is easy to prove why capacitive reactance decreases with increased capacitance. The more we increase ...
22 views

### In a RCL circuit; where V_C > V_L is the phasor angle leading or lagging?

Is this example correct in stating that the phasor angle is leading by 38.323deg?
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### Why can't i calculate the Inductive reactance in this way?

Question: $V_1=40sin(1000t)$,what is the value of Inductive reactance? Solution : $Z=\frac{V_1}{I}=\frac{40}{8}=5$,so $5=\sqrt{R^2+X^2_L}=\sqrt{4^2+X^2_L}$,so $X_L=3$ But i want to ask ...
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### What frequency is Ferrite Bead reactance usually given at?

I've noticed on schematics at work, when I was at uni, and on datasheets that Ferrite Beads usually (90% of the time) are only given with their designator (FB? or L?), then the reactance (XOhms) and ...
3k views

### Voltage across capacitor/inductor in RLC circuit

It is said that voltage across capacitor/inductor is higher than the applied AC voltage. How?
276 views

### capacitive reactance in a stranded wire

Can a stranded wire exhibit a capacitive reactance? I measured the real and imaginary part of a piece stranded wire using an old LRC meter( HP 4284a). Applied an open loop and a closed loop ...
501 views

### Understanding loudspeaker impedance

If I am correct, a typical loudspeaker's impedance will change depending on frequency. The impedance will be comprised of the resistance and the reactance of the voice coil. As frequency increases, so ...
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### Properties of an Ideal Transformer and the reasons behind them

Why should the magnetising reactance of an ideal transformer be very large i.e. approach infinity? What practicality does this imply?
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### At what frequency will the reactance of a 200mH inductor will be 5kΩ? [closed]

I'm doing practice exam questions, I have no idea what formula applies to this question. I know Xl = 2πf*L, but the question is asking for the frequency, how can I complete this when the formula for ...
455 views

### Gain factor in real Resistance and Reactance (AD5933)

I'm trying to develop a system for bioimpedance measurement with the IC AD5933. The AD5933 is a high precision impedance converter system that combines a frequency generator with a 12-bit, 1 MSPS, ...
290 views

### Is current calculation in copper wire for AC simple or not?

I'm trying to learn electronics by myself, and I'm starting with simple current calculations. Let's assume we have a straight wire of length L connecting a source and a sink. I know the voltage (V), ...
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### Why inductive and capacitive reactances have opposite signs and why they cancel out eachother?

For example in a series RLC circuit with ac source why total reactance is inductive reactance minus capacitive reactances ? I dont need any mathematical proof. Can anyone provide me a a logical ...
543 views

### Complex reactance formula explanation

Can someone explain the math behind the following relationships between the equalities in a capacitor's reactance? $$X_C = \frac{1}{2\pi f C} = \frac{-j}{\omega C} = \frac{1}{j \omega C}$$ For ...
121 views

### Finding total impedance

I have a circuit as shown below simulate this circuit – Schematic created using CircuitLab Where R1, R2 are resistors. jX1 and jX3 are reactants, and jB2 is admittance. That being said, I'm ...