Questions tagged [math]
Math or Mathematics is the abstract study of topics such as quantity (numbers), structure, space, and change.
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Why does tan (θ) equals -j in impedance of reactive circuits?
I'm having trouble understanding the maths for impedance.
Suppose we have a voltage of \$V(t)=V_{0}sin({\omega}t)\$ and we plug this into the capacitor equation \$I(t)=C\frac{dV(t)}{dt}\$. This would ...
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Beat frequency - Square signal
This question comes from this one, LTspice - Beat frequency:
It appears that when I did a FFT of two sinusoidal signals, there was no what is called beat frequency.
When I do the same exercice with ...
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LTspice - Beat frequency
Here is the theory from wikipedia:
Here are my summation of sin on LTspice:
The frequencies are 100 kHz and 120 kHz on the FFT. There is no frequencies at (f1+f2)/2 and no frequencies at (f1-f2)/2.
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Where am I wrong in my derivation of RC charging circuit equation?
I'm trying to derive the RC charging circuit equation for capacitor voltage \$V_C\$ and charging time \$t\$. Here's my solution,
We'll start by assuming the battery, resistor and capacitor are ...
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How is CRC5 calculated in detail for a USB token?
How is CRC5 calculated in detail for a USB token?
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How to find the power factor of a component when the combined power factor and one other power factor is known? [closed]
Problem:
A 2000 volt-ampere with a power factor of 0.8 lagging is combined with 500 volt-amperes of
synchronous motors. If the overall power factor is 0.9 lagging, find the power factor of the
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Polarization Derivation
Can how I can find the phi and theta unit vectors as described (Eq. 4a and 4b) in the following paper on antenna cross polarization? I thought the thetha and phi unit vectors were the same as those of ...
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How do I relate input and output signals and find the output for other input signals in LTI system?
I am studying about signals and systems. I came across a few practice problems. For the below question, I was able to mimic the input and output waves shown in ...
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How do I represent a signal as the real part of complex exponential and find the value of complex amplitude & complex frequency?
Context:
I was solving some practice problems and came across this problem. I know the complex exponential is:
$$ s(t)=Ae^{i({\omega}t+{\phi})}{\Rightarrow}Ae^{i{\phi}}e^{i{\omega}t} $$
Where \$Ae^{i{\...
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Why does this battery use 4.2 V when its nominal voltage is 3.7 V?
I changed my headphone power circuit and I noticed it was using 4.2 V to charge a 3.7 V battery. I am confused why it is using 4.2 V.
I know to charge a battery you need more voltage than its rating, ...
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How to analyze a current sink for an ideal power amplifier
In preparing a design for a MOSFET RF Power Amplifier, I analyzed this idealized circuit:
My analysis is in some ways consistent with simulation but in some ways gets very different results. Is my ...
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What is the reactive power of a capacitive circuit?
I want to understand the reactive power in a purely capacitive load. Surprisingly, I couldn't find the formula for this anywhere, so I derived it myself, and would like to ask 1. Is this formula ...
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Clarke transform seems to result in more current
I am looking into the Clarke transform for a balanced three-phase system (BLDC motor) and from all that I read, it tries to preserve magnitude. So if I apply this to the case of transforming three ...
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How can I do inverse Laplace of this transfer function to get the step response of the RLC circuit?
I have found this to be my transfer function for the circuit. I have tried doing partial fraction decomposition, but I end up with an s on top which I don't understand what to do with.
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How to derive a generalized equation with respect to time for voltage across the inductor & current in an RL circuit with a DC PWM source?
Circuit connection:
I have this resistor (96 Ω)-inductor (990 µH) circuit connected to a PWM source of frequency 62.5 kHz; And ...
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