Tagged Questions
2
votes
1answer
122 views
Calculating engine starter’s energy use
During a discussion on start-and-stop vehicle technology some bloke began pushing the point that re-starting the car uses stored energy from the battery, which needs to be replenished by increased ...
3
votes
3answers
164 views
Why is electrical energy so difficult to store?
Does anyone know a general answer to these questions? (I've asked them together because they're all pretty related, it seems.)
Why is it that we find electrical energy so difficult to store? Do we ...
4
votes
3answers
143 views
If an electric car were to drive without having to stop, would the range be greatly affected by the speed at which the vehicle is moving?
Of course aerodynamics factors into this question, and the faster you are moving the more air you have to push out of your way, the more energy you use. But would the difference be only a small ...
5
votes
2answers
159 views
What's the difference between Capacitors, Ultra-Capacitors and Batteries
Capacitors are known to hold and release energy very quickly, unlike the slower release that batteries exhibit. If one were to bunch many (1000's of) capacitors together could they function as a ...
2
votes
2answers
82 views
Lightning driven electrolysis
Could a lightning bolt be harnessed to perform electrolysis, would a useful amount of hydrogen be produced?
I'm imagining some industrial scale device in the ocean with some hydrogen capture ...
3
votes
1answer
290 views
The possibility of free electrical energy?
Please excuse my lack of knowledge/understanding.
Question: Why Nikola Tesla's Free Energy concept was never worked upon? Even today.
Context: Now that we know Nikola Tesla was a genius and did ...
0
votes
1answer
175 views
Faraday's law and superconductivity
According to Faraday's law of induction, volts = -Number of coils in a solenoid * change in strength of magnet / change in time. This doesn't take into account distance or speed, only time. If amps = ...
0
votes
1answer
92 views
Do you think it’s possible to make a power plant of the described kind?
We are working on a science project and try to engineer a power plant of a new kind. It is called Air HES (air hydroelectric station). The idea is described on our website.
Do you think it is ...
0
votes
2answers
91 views
Does using batteries in a series raise the overall Wh's of the batteries used? Why/Why Not?
If one has 2 batteries of 6 Volts each with 500 mAh each, then separately the batteries should provide 6 Volts * 500 mAh = 3 Wh each or 6 Wh total. However would it be the case that if someone where ...
2
votes
3answers
310 views
How does energy depend on frequency in an alternating current circuit?
In what relation is the energy input in an alternating current circuit to its frequency?
I'd guess I have to compute something like
$$E=\int P(\omega,t) dt=\int U(\omega,t) I(\omega,t) dt, $$
but ...
0
votes
2answers
310 views
How can you measure battery output to see if the wattage is accurate? [closed]
When you have a battery and it shows you the milliamperehours and volts. You can use those to calculate the wattage. How can you test the battery to see if its wattage is accurate or if the company ...
0
votes
1answer
917 views
Battery Calculations [closed]
I have been given the following statistics for a battery and I have been asked to find the
1) battery capacity in Wh
2) volumetric energy density in Wh/cm3
3) gravimetric energy density in Wh/kg.
...
0
votes
1answer
179 views
Tubelights+power lines pictures?
I've come across many pictures like these, sometimes in chain emails reporting the dangers of power lines.
Another claim is that they run on "wasted" energy.
The explanations given are that the ...
2
votes
3answers
1k views
How much energy was consumed when we turn on/off light?
My parents told me to turn off the light when I am not using it. But I remember my physics teacher told me that the action of turning on/off a light can cause huge energy. I am wondering how much is ...
0
votes
3answers
163 views
Lightning Power?
What is the power source of a lightning? It doesn't consume fuel, nor an atomic fission/fusion, but it discharges a large amount of energy. Is it feasible to create an artificial lightning using the ...
1
vote
1answer
4k views
How much energy is in a lightning strike?
According to Wikipedia an average lightning has 1TW, the whole world used 16TW in 2006. (I suppose this means the same as 16TWh in one year?) Sometimes the lightning reaches 100kA. This peak last for ...
3
votes
1answer
322 views
Is there something like the Poynting vector for hydraulic circuits?
The Poynting vector is a representation of the energy flux in electromagnetics, showing the amount and direction of power flow at different points in space. In electric circuits, the energy is not ...
1
vote
1answer
407 views
How to teach the concepts of “Electric Potential” & “Potential Energy” to 10th grade students
I've got to teach the concepts of "Electric Potential" & "Potential Energy" to 10th grade students. I don't understand how to express these things and make them understand.
“If you can't ...
0
votes
3answers
9k views
Charging 12V 150Ah battery
I want to charge a 12V battery of 150Ah with a solar panel. The solar panel specs is
12V, 25 Watt.
Can anyone please provide me how to calculate that how much time it will take to charge the battery? ...
2
votes
2answers
203 views
Small scale water power, how does water volume and hight convert into electric energy?
I was playing a little bit with the basic physics behind water power production but I can't get the numbers right.
Let's say that I put a windmill that pumps water into a watertank on the top of my ...
2
votes
2answers
891 views
Why is the steam from cooling towers not used?
If I see the steam coming out of cooling towers at an altitude of 200 meters, I cannot help but think that this energy is wasted. My question is: Why isn't this steam cooled enough to become water and ...
0
votes
0answers
74 views
How do we deal with the intermittence of solar and wind energy? [closed]
We know that solar panels don't work at their best under cloudy skies. Wind turbines also don't turn when the wind doesn't blow. I like to imagine a 100% renewable energy portfolio (solar PV/thermal, ...
