Questions tagged [energy]

Energy is defined as the amount of work that can be performed by force, measured in Joules. Energy is Power over Time. This is a poor tag to use. Please consider if your question relates to Energy as defined in physics, not as a synonym for Power or capacity.

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Is there such a thing as a 'Constant Power Source'?

Academic question: Is there such a thing as an electrical constant power source, which delivers energy at a fixed rate? Specifically ... there are voltage sources and current sources, which maintain (...
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1answer
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Storing data of 1-phase Energy-meter in External EEPROM (Suggestions on data format) [closed]

I'm developing a Smart Single-phase Static Watt-hour Energy-meter using Renesas RL78/I1C MCU. I have a parameters list which needs to be stored in external EEPROM every 2 minutes. While doing so, I ...
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4answers
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LTSpice sweep resistance

I would like to plot the power obtained by this simple recovery circuit (UR1eff^2/R1) according to the value of the resistance R1. But as it is a sinusoidal function, it takes the average value of the ...
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SSHI circuit on LTSpice

I've been trying to get an SSHI circuit running on LTspice for several days now (see below schematic). My problem is the following: the simulation (.tran) stops after a hundred milliseconds. Being a ...
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1answer
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Energy meter neutral current measurement

I was reviewing an energy meter specification and I came across neutral current measurement. What is the importance of neutral current measurement in an energy meter for three phase power supply? I ...
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3answers
129 views

Why can't we use magnets to create energy like this?

Won't it rotate continuously? Why can't this happen? Energy cannot be created, right? Then will the magnets degrade over time and stop being magnets? But they don't have their own energy also. Then ...
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46 views

Problem in Computing the Energy in Energy Meter using ESP32

So me and my groupmates are been working on with our thesis project about energy meter. In our project, the esp32 is the main board we are using. We also have voltage sensor (ZMPT101B) and current ...
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2answers
75 views

What depletes batteries

I recently learned how how energy actually flows in batteries, the electric and magnetic fields create an energy vector pointing into the circuit at all points and out of the battery. This broke my ...
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1answer
43 views

Power and current contradictions in transformer secondary

Two contradictions that I couldn't find a solution for regarding a transformer: For an ideal transformer, from conservation of energy we can say that: V1 * I1 = V2 * I2 Where V1, I1 are the primary ...
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1answer
67 views

Can I charge a 16V 16.6F supercapacitor with an 18V solar panel?

I'm working on my calculus project (I recently started college) and my topic is using solar panels and supercapacitors to help mitigate the lack of energy/electricity in the rural areas in my region. ...
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5answers
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Voltage drop through a resistor for a single charge, contrasted to a non-ohmic component

Recently I have been reading about how transistors and diodes only drop a limited amount of voltage across their leads for a wide range of currents. So the voltage drop per charge (at a given ...
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4answers
113 views

Energy conservation when adding braking resistor to H bridge?

This may be a stupid question but I'm missing something fundamental about energy conservation of electrical machines - I am sure I have forgotten something from basic machine theory but I haven't ...
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0answers
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Impact of reduction on Dynamic energy and dynamic power in microprocessors

A microprocessor has been designed to have a dynamic switch which reduces power consumption when the loading reduces. Assuming a reduction of 20% in voltage reduces clock frequency by 20%. Calculate ...
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0answers
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Calculate residual energy in rpl.mhrof.c code in cooja

I'm working in develop of rpl protocol I want to calculate residual energy in rpl.mhrof.c code in cooja, some one here know the c code of residual energy of the nodes please?
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1answer
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How does this under voltage lockout (UVLO) work?

In my project, I need an under voltage lockout (UVLO) to connect the load electronics to the energy-storage element via a power-gating transistor when the voltage across the supercapacitor exceeds ...
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0answers
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Minimal start-up current of a PV inverter

In the datasheet of PV inverters, typically (only) a minimal start-up input voltage is given, e.g. for an SMA Sunny Boy the datasheet indicates 100V/125V. However, why isn't there a minimal start-up ...
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0answers
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Piezo cantilever energy harvester: how to mesure such small power?

I am currently designing a piezo energy harvester and I would like to modify the resonating frequency to maximize the energy recovered(for exemple by changing the center of mass of the cantilever). My ...
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0answers
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Getting most power from low voltage solar powers, each different angle

I have a specific problem. I have 10 small solar panels, each max 5.5V and 100mW power. Each one is at a different angle. I want to get the most power out of it. Cost is not really a problem, but I do ...
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1answer
56 views

Power and Energy Computations in the Frequency Domain

How do you calculate the power and energy of a signal given only the frequency domain form of the signal function? For the purposes of this question, please do not assume that it is possible to find a ...
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2answers
48 views

Why do n-type materials have a smaller conduction energy band?

I looked at "Why does a p-type conduction band have higher energy then n-type conduction band in a p-n junction?" and am still confused. From the image above we can see that the conduction ...
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1answer
47 views

Drawing energy from a 3.7V LiPo battery while simultaneously charging with a solar panel

I have a 200mAh 3.7V (0.7W) LiPo battery that I am looking to use as an energy source for a large model airship. I also have a 7.2V 100mA (0.72W) solar panel that I would like to use as a means of ...
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0answers
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How to find the dynamic energy of a processor without using capacitive load?

I have the following question: A cell phone performs very different tasks, including streaming music, streaming video, and reading email. These tasks perform very different computing tasks. Battery ...
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1answer
57 views

What is the average energy loss if a booster connected to power source but without a load?

I have lipo battery 4.2V 3000mAh, booster simulation ti power bench TPS55340QRTERQ1 ‑ 2.8V-4.2V to 8.00V @ 1.5A Vin 2.8V - 4.2V Vout 8v Iout 1.5A simulation details efficiency 84% 1.43Mhz duty 65%...
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0answers
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My first full contact-less power meter doubts

I need to measure power consumption of an industrial machine, it is supplied with 3-phase plus neutral connections, 220V per phase. They said there is a voltage stabilizator device between the power ...
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1answer
70 views

Can a machine be powered with food energy? [closed]

Would it be possible, in principle, to create a machine that digests food in a similar way as humans do, extracts energy from the food, and stores it as electrical energy in a battery to power its own ...
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0answers
23 views

Force of linear electromagnet in relation to length of an air gap

I am confused by derivation of relationship between force of linear electromagnet and length of a core air gap. I have found one source http://info.ee.surrey.ac.uk/Workshop/advice/coils/force.html#...
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2answers
52 views

Confusion in selecting number of state variables

Generally we take no. Of state variable equal to number of independent energy storing elements , let's take two examples - 1.a RC circuit with voltage source as an input ,so here we can take ...
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2answers
68 views

Where is electrostatic potential energy stored in a capacitor system?

We know, $$U = \frac{ \epsilon_o}{2} \int_{\partial S} |E|^2 \mathrm{dV}$$ Now, suppose you have a capacitor system of the geometry as shown below, I know energy is stored between plates of a ...
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3answers
59 views

If greater potential energy is toward pos charge, then why PN energy band diagram show lower energy toward pos charge across depletion region?

If in an electric field, greater potential energy and voltage are toward the positive charge and away from negative charge, then why do PN energy band diagrams indicate lower energies toward the ...
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1answer
69 views

Power calculation

Let's say I'm gonna charge a 1mF capacitor from 0 to 100V in 10 seconds. Assuming there's no limiting resistor nor any other losses, the total energy that must be tranfered from the 100VDC supply to ...
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1answer
59 views

Derivation of energy in capacitor

While searching for something totally unrelated to this, I came a cross a website that derived it in this fashion: the instanteous power in a capacitor is given by $$p_c= v_c(t)\cdot i_c$$ since $$i_c(...
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2answers
102 views

Power factor improvement [closed]

There are 3 resistive bulbs (60 watts each) in series fed by 230Vrms from the transformer. If I apply capacitors in parallel with load I will get more Voltage. The more capacitors, the higher the ...
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1answer
56 views

Power factor down after solar connection

We installed solar plant in factory. After that power factor goes down to 0.16. Normally it never goes below 0.85 in history even if we keep APFC off. We always maintained it to 0.99. Note - Main ...
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1answer
40 views

Difference in electrotherapy Lifepak 12 [closed]

I'm a beginner medicine student and I've got a question out of curiosity, why in defibrillators lifepak 12 or other versions..paramedics or dictors set energy for defibrillation and cardioversion in ...
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1answer
90 views

How does a relay or switch work with batteries or capacitors?

I am charging my capacitor so it can act as a battery for a short period of time. I already did the calculations for the battery discharging and charging. My problem is now that I have a load, I want ...
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3answers
459 views

What is reactive energy?

We know the typical equation for instantaneous power (which can be proven): \$p(t)=v(t)i(t)\$. In sinusoidal steady state (let's ignore harmonics for simplicity), \$v(t)=\sqrt{2} V_{\text{rms}} \cos{(\...
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1answer
107 views

Is this scenario an efficient way of generating electricity?

I will try my best in order to provide information which could help you imagine the scenario. Accurate results are not compulsory. I am generating electricity using a 5kW alternator but for the ...
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0answers
33 views

How to calculate Energy Readings in DALI-2?

I'm reading the memory bank202 from a DALI-2 supported led luminary for energy consumption. When the lamp is on, I see that memory bank location 9 and 10 is increasing. But I couldn't understand how ...
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1answer
80 views

Understanding relation between energy use, watts and amps

I'm looking into air conditioners and I've been unable to fully understand the relation between watts, amps and the energy ratings (in this case, the one used in the United States, the yellow Energy ...
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2answers
55 views

Fast method to calc th Fourier transform

exist a fast method to calc the Fourier trasform (in both sense, t -> f and f->t)? When I use the table and the properties of the Fourier transform, sometime I have difficult to calc this... Any help ...
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3answers
35 views

Power calculation help

I have a hardware setup that provides me with power being consumed every second so I get somewhat of a different reading every second. Using these per second readings how do I calculate kwH?
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2answers
57 views

Capacitor's energy required for a predetermined drop in its voltage - with LDO and constant current elements as load

I am trying to understand how much energy a circuit (composed by some passives here called analog, and an MCU) will require. The system is powered through a capacitor, and the "passives" are actually ...
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0answers
30 views

Battery Ah specs vs actual Wh when charging and discharging

It is ubiquotously stated that Wh = Ah x V. While this is true (at least regarding the units) I have some doubts about the practical aspects of it. Using an example: Let's take a fully discharged (0%...
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4answers
63 views

Energy Transport in Circuits

I've been reading about how energy is actually transported in circuits (I first read about it here: http://amasci.com/miscon/ener1.html). The description in this article of why electrons don't move ...
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1answer
79 views

How do we have the \$E=\frac{1}{2}L_1I_1^2+\frac{1}{2}L_2I_2^2 \pm MI_1I_2\$? Can anyone show me its proof?

What is the total energy that two inductors store? Solution \$R_{th}=(12||6)+6=10Ω\$,so \$I=\frac{90}{10}=9,I_1=9\times \frac{6}{12+6}=3,I_2=9\times \frac{12}{12+6}=9\$. So the energy that two ...
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1answer
49 views

Capacitor charging and energy

Assume I have a capacitor with capacity \$C\$ and is charged to a voltage level \$V_a\$ and then discharged. 1) During discharge it dissipates \$E\$ joules of energy. What is the equation to find ...
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1answer
96 views

Voltage without amps [closed]

I have just read an article on electricity extracted from the atmosphere. Apparently there is a massive supply of collectible voltage available from the air. However the amps available is very low. ...
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2answers
96 views

Might an x-ray tube have the capability produce more power than it consumes?

In transformers, when the voltage is powered up, the current is proportionally powered down. In the x-ray tube’s transformer, this also happens. However, the current of an x-ray tube is not the ...
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1answer
38 views

Interfacing Arduino for variable power supply

I'm a mechanical engineering student with no knowledge on Arduino microcontroller. I am currently working on a project of using Artificial Neural Network in a hybrid solar heating system. The hybrid ...
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0answers
41 views

Calculate time energy is stored in capacitor

I have this problem: I've calculated A) to be 8 nJ, and my Vc(0) = 4 V and Vc(∞) = 0 V. I tried using the wc(t) = 1/2CVc^2 formula to calculate the time when the energy of the capacitor is 1 nJ. ...

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