All Questions
65
questions
1
vote
1
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68
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Potential energy of a uniformly charged parallel plate capacitor filled with dielectric
For a uniformly charged parallel plate capacitor (dimensions l × w × d), its potential energy is given by:
$$ U = \frac{Q^2}{2C}\ $$
Now if we insert a material (dimension x × w × d) of dielectric ...
1
vote
1
answer
161
views
CMOS (Energy Supply of voltage) [closed]
Can someone please explain why, when \$ln\$ is transitioning from low to high, the energy supplied is \$C_{vdd}\cdot V_{dd}^2\$?
0
votes
1
answer
104
views
Energy reservoir capacitor
How to calculate the appriopriate capacitance for an energy reservoir capacitor that would serve as an alternative IC power supply in case of main power supply failure. Is there a specific formula or ...
- 89
1
vote
2
answers
462
views
Energy in capacitor paradox
Recently I have been thinking about a circuits problem that caused me a lot of confusion.
First of all we know from thermodynamics that energy is conserved. I wanted to show a problem that seemed to ...
- 179
13
votes
5
answers
4k
views
Why do capacitors have less energy density than batteries?
The basic operating principle of a battery is, in order to charge it, the electrons are removed from cathode and moved to anode by applying voltage. And to discharge, the electrons move from cathode ...
- 249
1
vote
1
answer
65
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Boost Converter - Coil energy transfer into Capacitor - Help needed!
I am trying to design my own boost converter and so am learning about coils.
Let’s consider this example:
The switch of our boost converter has just opened, there was 100 mA flowing though the coil, ...
- 45
0
votes
1
answer
107
views
The two capacitors are in series but positive end of one plate is connected to positive end of the other
Like the title says, my task is to find the initial voltage across the terminals. The two capacitors are in Series with positive end of one plate connected to that of another.
The given information ...
- 153
0
votes
1
answer
96
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Find suitable charging voltage for capacitor based on energy and time required for discharging
We need to calculate the charging voltage required to dissipate a certain amount of energy via R-Load.
The problem will be as follows:
If we need to dissipate 400 J through the R-Load in a time period ...
0
votes
3
answers
1k
views
Are two capacitors connected together considered to be parallel or series?
If both ends of two capacitors are connected to each other but in such a way that the positive end of one capacitor is connected to the negative end of another capacitor, do we say that the capacitors ...
- 153
0
votes
1
answer
50
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Is this method of proving energy is conserved in an LC oscillator correct?
Assuming no energy loss due to heat or EM waves
$$U=\frac{Q^2}{2C} +\frac{LI^2}{2}$$
differentiating both sides with respect to time,
$$\frac{dU}{dt}=\frac{QdQ}{Cdt}+IL\frac{dI}{dT}$$
but we know that ...
4
votes
1
answer
666
views
Power loss in a capacitor vs inductor
Is there are a general rule of thumb if one of these stores energy more efficiently than the other?
When properties are approximateily comparable, are energy losses bigger with a coil or with a ...
- 43
2
votes
4
answers
3k
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A capacitor charge time - two methods two different answers
I am a bit puzzled and ask for your help about the following:
A theoretical capacitor of 100 F is being charged with a constant power source of values V = 50V, I = 50A, ESR of capacitor = 5 mohm
To ...
- 33
5
votes
6
answers
3k
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Why can't current change instantaneously in a given inductor?
I know the mathematical reason behind this. Given the inductor I-V characteristic we know that:
I understand mathematically that a function which is differentiable must be continuous, but what is the ...
- 163
0
votes
1
answer
390
views
Magnetic energy harvesting with a current transformer
I am planning to design a magnetic energy harvesting circuit with a current transformer (CR8349-1500) to charge a super capacitor.
Load current rating is 0 to 35 amperes. From the current transformer ...
- 87
11
votes
6
answers
2k
views
Why is the energy in a battery QV, but the energy in a capacitor QV/2
If I know the total charge in a battery, let's say 5000 Ah, and I want to find how much energy is stored in the battery, I multiply the total charge by the voltage E = Q·V; for example, for 12 V I ...
- 153