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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How could a rechargeable battery charge itself without an external source?

While I was working on my graduation project I had to charge a rechargeable battery then discharge it and so on.I was shocked when the battery charged itself without any other external sources for ...
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3answers
71 views

Capacitor vs battery which cost less per capacity? [closed]

I know that batteries have better density ie capacity per volume. But I want to get the most energy capacity for the money. Which one would would you get? I'm trying to store energy from solar for 1 ...
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1answer
77 views

Why are batteries measured in electrical charge unit (ampere-hour) and not in energy unit? [duplicate]

I've searched for an answer for this question for a long time. Specifically I've found this thread which is closely related to my own question: Why are batteries measured in ampere-hours but ...
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1answer
25 views

Energy in transients vs. steady state

In something like a regular household, how much energy consumed is transient power vs steady state and what kind of frequency distribution does it have, roughly? I imagine the vast bulk of the energy ...
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1answer
57 views

How can cities save electricity? [closed]

So I read about exercise equipment that produces electricity but very little, is anyone working to improve on it? I feel like this has a lot of potential to fight obesity and save on electricity no ...
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4answers
76 views

Is it possible to measure energy consumption from power socket? [closed]

I wanted to know if it is possible to measure how much energy is being consumed in the entire house by plugging in a power meter in any power outlet in the house? I am aware of some portable meters ...
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3answers
113 views

Can we use use an oscillator as a low power source?

Is it possible to make an oscillator (or buy an oscillator IC) that can give directly (without using a power amp) up to 2W (or even 1W) of power? And if not, then what stops oscillators from getting ...
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2answers
49 views

Energy absorbed by the condenser

If the current \$i=0\$ the total energy absorbed is: \$E_{tot}=E_C+E_L\$, where \$E_C\$ is the energy absorbed by the condenser and \$E_L\$ that absorbed by the inductor. Now: \$E_C=\frac{1}{2}C ...
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1answer
54 views

Taking into account power factor when calculating energy savings

I am attempting to calculate the energy savings of a fan motor after a new runner and inlet cone was installed which claimed to improve fan efficiency. I have logged amp draw before and after the ...
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2answers
271 views

How do residential analog and smart meters meassure power?

Im building my own digital meter in order to upload the data to a sql database, up to now i know that there are several parameters being meassured into a digital wattmeter: volts, current, apparent ...
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1answer
93 views

Does electric potential influence the direction of current?

Main goal My main goal right now is trying to understand what negative voltage means, since I know AC can have a negative voltage and so can any electric component. I've pretty much read and seen ...
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0answers
67 views

Compressor capacity vs input power, Kelvins law

Have got a silly confusion regarding efficiency calculation of AC & Ref. compressors. Here is a sample of specs of an Aspen miniature compressor. ...
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1answer
107 views

2600mAh Battery Charging Time

I've spent a very long time trying to work this out, but some websites seem to conflict the information - or I'm completely missing the point. I have a rechargeable battery: 2600mAh 4.2V max charge ...
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4answers
547 views

Why and How does Power Plant generate Watts?

I know my question is stupid, it is stupid because I am not understanding it correctly. I thought two of following is required to calculate watts. Voltage, Current or Resistance/(Impedance in AC) is ...
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1answer
179 views

Will repeatedly turning a light bulb on and off damage it?

I have been hearing a common saying that if one keeps switching the lights on and off you will probably damage the light bulb itself, since every time you close the switch there would be a sudden rush ...
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4answers
155 views

how much energy is required to create a sound with constant frequency and amplitude?

Ok, this is a theoretical question, (Forgive my poor English, I am not a native speaker). Lets assume that I have a power-source with p unknown. this power-source provides energy to a speaker to ...
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1answer
172 views

Energy stored in a battery, formula?

Consider schematic below. simulate this circuit – Schematic created using CircuitLab With a DC source we can use this arrangement to find the force between the plates of the capacitor. ...
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3answers
324 views

Are Neo generators a Scam or not?

After reading the FAQ page of Neo generators, I became incredulous of this particular part (translated from Spanish): HOW DOES IT WORK INTERNALLY? Our optimized system collects the abundant ...
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2answers
398 views

How do I, as a consumer, gain or lose when the utility company line voltage varies from rated value?

A little background; the line voltage supplied here in my part of India varies as a function of the load. At dusk, the measured value is as high as 248V. Household appliances are rated at either 220V, ...
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1answer
62 views

how to compute power of a device

how to compute power?, energy expended in joule? the battery is 3.6V, the device has a voltage reference which keeps voltage flowing through the circuit constant at 2.5 V, average current is 0.005 A ...
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2answers
62 views

How exactly does the grid handle small deviations in power consumption?

I've heard many times that the grid electricity production and consumption must be balanced and imbalances lead to overvoltage or undervoltage. I've never seen an explanation of that phenomena from ...
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1answer
119 views

Derivation of power and energy in a capacitor

I have two very related questions: In the derivation of power in a circuit we can do the following: \$P=\frac{dw}{dt}=\frac{d(QV)}{dt}=Q\frac{dV}{dt}+V\frac{dQ}{dt}\$ and then assuming that \$V\$ ...
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3answers
105 views

How can we reduce the amount of energy consumed by a large number of electrical motors in a factory?

if we suppose we have an electrical installation in which we have 1000 motors, and we want to reduce the amount of energy consumed by those motors. where can we start and what do we need to do ? what ...
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3answers
246 views

What does a 200MW capacity power plant mean?

1W is 1Joule of energy transferred in 1sec. So what does a 200MW capacity power plant mean? Does it mean it generates 200MJ of energy in one second. But then I have also read it can mean 200MW of ...
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2answers
113 views

How much energy does cache memory consume in a modern processor? [closed]

What fraction (on average or range) of total processor energy consumption does the cache subsystem consume in modern processors (say post 2009)?
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2answers
54 views

Energy Absorption By Series Resistance During Cap Charging

This question formed while trying to size a NTC thermistor to limit the inrush current to a capacitor. Assume the schematic below (with a fixed resistance): simulate this circuit – ...
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1answer
112 views

Is the sun enough to power all of our needs? [closed]

If so why isn't solar power being implemented more so? I don't mean to as a govt conspiracy post. But what's holding us back from achieving this, if it is indeed possible.
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2answers
690 views

How to calculate the Back-EMF energy on an Inductor?

The Back-EMF generated by an inductor in Volts is: \$V = -L\dfrac{di}{dt}\$ Where \$L\$ is the self-inductance and \$\dfrac{di}{dt}\$ the rate of current change. Now, let's say I want to store those ...
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3answers
226 views

How does a constant current (CC) power supply regulate voltage (V) in parallel circuits?

I see that some power supplies provide a wide range of output voltages meanwhile maintaining the current. For example: 2.7 A, 20-36 V output. I understand that the voltage rate will depend on the ...
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1answer
56 views

Comparison of 180nm and 65nm CMOS technology in consideration of delay, power and energy consumption

how would each of them typically compare with respect to delay, power and energy consumption? (Used in digital circuits)
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2answers
199 views

How do I design a current transformer?

I want to make a Current transformer using toroidal ferrites to measure 220/50-60Hz AC current(40A max). Is it possible? And how can I calculate secondary turns count? Ferrite properties: H = 2000, ...
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1answer
110 views

Can an electron carry only one charge?

Sorry if this has been asked before. Could also be a really basic question (new to electrical study). I am a bit confused about the relationship between electrons and charges. So what I understand is ...
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1answer
86 views

How to use a graph of a wavefunction (psi) to create an approximate graph for potential (U)?

I don't understand how the top graph was used to approximate the bottom graph, could someone please explain to me what was going on? I know that in regions 1, 3, 5, 7, there is no oscillation and ...
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2answers
113 views

Why monitoring power and energy in energy usage meters?

This time my question about the how power companies monitor usage. We get electric usage bill in [Kilo watt hour]/Energy. What should be looked up on for monitoring the usage the instantaneous energy ...
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1answer
145 views

Can I extrapolate the rated overload spec of a wirewound resistor to a joule rating?

I'm considering using a Vishay FVT series resistor for precharging some capacitors. Capacitance: 3300uF Voltage: 730V Resistance: 500 ohms Resistor continuous wattage: 25W This series, like many ...
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1answer
49 views

Energy state of transistors

Are there any energy states of transistors? i.e. zero energy, high energy etc. If that is possible, can't we employ the configurations of transistors such as storing memory as energy sources? That ...
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1answer
610 views

How big should battery be to power two strips of led for few hours?

I have an idea for halloween costume for upcoming Halloween. It will involve building two small sets of infinity mirrors. I am completely new to the electrical engineering. The infinity mirrors ...
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2answers
179 views

Electrical energy in a fighter aircraft

A car uses a car battery and an alternator powered by the engine. But where does the electrical energy for fighter aircraft comes from to maintain the onboard systems? And which voltage and frequency ...
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2answers
299 views

Harvesting Back EMF Possible?

Let me start by saying that I am not talking about the free energy or "overunity" idea of back EMF. When searching around for information I can only seem to find information from free energy sites, ...
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2answers
87 views

Energy direction in an electronic circuit

I've been reading a number of materials trying to understand the physics that allow electricity to be possible. I'm confused by this virtual positive [charged] particle (often called a test particle) ...
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2answers
205 views

Solar panel calculation

I have a small solar panel of the following, Area = 0.0078 square meter Rated Power = 1 W Now, I am interested to calculated the total energy this solar panel can harvest over a day. I am taking ...
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1answer
55 views

How to monitor produced energy?

I want to monitor energy produced by 250W solar panel. But I need some hints. Does anyone knows something? Is it possible using ACS758 chip or better I have to use current transformator? Finally I ...
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2answers
2k views

Theory behind the “Joule Ringer” circuit

The less-than-critical thinking free energy types are pointing to the "Super Joule Ringer" demonstrations online, where a quick touch with a 9 V battery illuminates an LED for hours. ...
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2answers
216 views

Charging capacitors in parallel with a battery

I am trying to figure out a system to charge a series capacitor bank without too much current going through the capacitors. I had the idea of putting a battery in parallel with the series capacitor ...
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0answers
169 views

Can't find Broadcom BCM4329 datasheet

I need to find information about my phone energy consumption and I can't find a proper datasheet about the BCM4329 chipset. Does someone have it? I'd like to create a power profile for PowerTutor in ...
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2answers
198 views

How to understand the “basics” of electricity? [closed]

I want to be a self-taught computer engineer ... massive goal, but it's what I want eventually. I check out textbooks and online resources, but I feel like I need a prerequisite somewhat -- I still ...
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4answers
400 views

Calculation of PV daily energy yield

How can you calculate how much energy a PV panel (known size and wattage) produces in a day given the exact insolation in kWh/m2/day?
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1answer
129 views

Can I connect my Philips sound system to my Samsung tablet? [closed]

I have a Philips SPA 4310/10 Sound System and I want to connect via 3.5mm jack to my 10" Samsung Galaxy Tab 3 P5200 to listen some music. Am I at risk of short-circuiting the tablet? Or will ...
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3answers
124 views

Why harvesting energy why not harvesting power?

I am wondering why is it called Harvesting energy and why not harvesting power? Energy is measured in Joules/s and power is Watt but the result is watt. For example if we harvest energy from sun or ...
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2answers
218 views

Tippmatic auto shut-off switch - how to use it?

Some products in my company are now required to use an auto shut-off switch to be compliant with new regulations in European space (European Eco-Design Directive ErP). I got word that the device ...