The power tag has no wiki summary.
32
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8answers
7k views
What practical issues remain for the adoption of Thorium reactors?
From what I've read on thorium reactors, there's enormous benefit to them. Their fuel is abundant enough to power human civilization for centuries, their fission products are relatively short-lived, ...
22
votes
8answers
2k views
Why don't modern spacecraft use nuclear power?
The Voyager 1 & 2 spacecraft launched in 1977 with Plutonium as their source of electricity. 34 years later they claim these two spacecraft have enough power to last them until at least 2020. That ...
9
votes
7answers
3k views
Why is a 1mW laser dangerous?
In our Physics lab we have a 1 milliwatt (0.001W) helium neon laser. Despite the low power, we were cautioned not to even look at reflections of the beam as it could cause permanent eye damage - why ...
8
votes
3answers
2k views
Why do power lines sag when they are heated up?
I was reading some information about the 2003 power blackout in the Northeastern US.
Beginning early in the afternoon of August 14, 2003 big transmission lines began to fail in First Energy's ...
6
votes
3answers
477 views
why aren't there nuclear powered aircraft?
I know this might sound like more of an engineering question that about physics, and it probably is, but bear with me: i'm still not sure if the answer to my question lies in the physics or in the ...
6
votes
6answers
538 views
When driving uphill why can't I reach a velocity that I would have been able to maintain if I started with it?
Consider these two situations when driving on a long straight road uphill:
Starting at a high velocity $v_h$, which the car is able to maintain.
Starting at a lower velocity $v_l$, and then trying ...
6
votes
2answers
428 views
Quantum Computing Power Advantages
Currently, the world's fastest supercomputer runs at 17.59 Petaflops, which consumes 9 megawatts of electricity. A qubit-based quantum computer has the potential to operate much more quickly for some ...
6
votes
2answers
579 views
Would the ionic wind power fence actually work?
Described here and in the references (patent, patent), the idea is to use a large fence as a grid electrode. Spray water droplets near a high voltage to charge them, and then the wind blows them ...
5
votes
1answer
309 views
What type of solar energy technology has the most future potential?
In terms of dollars per watt, using theoretical efficiency limits, what technology holds the most promise to become the primary solar energy capture technology?
My hunch is carbon-based modules, ...
5
votes
2answers
111 views
Averaging decibels
Wikipedia:
The decibel (dB) is a logarithmic unit that indicates the ratio of a
physical quantity (usually power or intensity) relative to a specified
or implied reference level.
If I ...
4
votes
2answers
191 views
How do you calculate power at the focal point of a mirror?
I'm a Mechanical Engineering student and I'm working on my senior project, so I need help. My project is about designing a solar dish having a diameter of 1.5 meters and a focal length of 60cm. so at ...
4
votes
4answers
704 views
Do resistor-based fan regulators save no power at all?
I have heard that the traditional resistor-based fan speed regulators are inefficient. In fact, I have noticed that such regulators tend to get hot when the fan is set to low speed. However, does that ...
4
votes
1answer
30 views
Have Sterling Engines Been Used In Outer Space?
I was reading about Stirling Generators having potential applications for power generation in outer space. Have Stirling engines ever been sent into space?
3
votes
10answers
1k views
Can a nuclear reactor meltdown be contained with molten lead?
If lead can absorb or block radiation, would it be possible to pump molten lead into a reactor core which is melting, so that it would eventually cool and contain the radiation?
Is there something ...
3
votes
2answers
300 views
What is a single word that describes the idea of the second time derivative of energy?
I think about position, its time derivative speed, and its second time derivative, acceleration. I would like to identify a single word that can be used as a handle for the second time derivative of ...
3
votes
1answer
190 views
Lifetime of battery
If I directly connect two terminals of 3V battery (negative to positive) using copper wire, would it lose all its charge faster compared to another 3V battery that is used to lighten a 1.5V bulb?
3
votes
1answer
99 views
Is it possible to get energy from electrical wire using induction?
Pardon me if this is a stupid question but my physics courses are from a long long time ago and I was a teenager back then. ;)
Electricity in a wire generates electromagnetism, right?
Would it be ...
3
votes
1answer
96 views
Can a solar thermal collector designed for use in homes ever power a stirling engine designed for use in homes?
Can a solar thermal collector common on private roofs today designed for collecting heat for the household ever collect enough heat to power a stirling engine of say this model: ...
3
votes
3answers
445 views
Loss of Power at high frequencies
One of my work colleagues told me that a cable he is sending a signal through is losing power at high frequencies. So he recommends the signal should be amplified before being sent. The explanation ...
3
votes
1answer
4k views
Is there any significance to 1.21 GW?
In connection with a related question on Science Fiction & Fantasy Stack Exchange page: does this number 1.21 GW make any sense? What is 1.21 GWatts? With what can you compare it? Can the ...
3
votes
4answers
319 views
Should we forget fusion and focus on geothermal power? [closed]
Firstly I can say that I would love us to come up with a sustainable fusion solution. However with the latest estimates being 2050 at the earliest for an effective fusion solution and the planets ...
3
votes
1answer
269 views
Calculating displacement amplitude of ultrasonic power transducer
I am not a physicist, but my current project drives me to some physics-related computations, hence seeking help.
I have some ultrasonic transducers, 5938D-25LBPZT, for which very limited information ...
3
votes
1answer
118 views
What are some ways that humans could have influence over what sequence a star was in?
How would a society go about either preventing our sun in its primary sequence from going into a Red Giant a billion years from now? Or perhaps, accelerating the process of going from main sequence ...
2
votes
4answers
1k views
How does power consumption vary with the processor frequency in a typical computer?
I am looking for an estimate on the relationship between the rate of increase of power usage as the frequency of the processor is increased.
Any references to findings on this would be helpful.
2
votes
3answers
381 views
Nuclear physics problem, Why do we use high weight atomic elements?
So as far as I know, nuclear fission uses high weight atomic elements to manufacture power. If the risk of runaway reactions are a major reason for not expanding this technology, why don't we use ...
2
votes
2answers
288 views
Harvesting electricity in the air from power lines:
Recently I came across this quote on the internet, about a person who apparently set up devices to extract electricity from the "air", on his own property:
I read an article a couple of years ago ...
2
votes
2answers
622 views
What is the luminosity per square meter hitting the Earth's surface from the Sun?
So I know that the Sun's luminosity is $3.839 \cdot 10^{26}$.
What I want is the luminosity per square meter at the Earth's surface. So this is what I have got so far:
I know the distance to the ...
2
votes
2answers
281 views
Lorentz engine to run a car?
Could a Lorentz engine (like the ones that move the write head inside of hardrives) be used to run car ? Would it be possable to get it producing 60hp, and a decent amount of tourque, if so how large ...
2
votes
6answers
344 views
Confused about unit of kilowatt hours
So I am a little confused on how to deal with the Kilowatt hours unit of power, I have only ever used Kilowatts and I have to design a residential fuel cell used as a backup generator for one day.
...
2
votes
2answers
314 views
Why doesn't a phone charge faster, rather than slower when it is in use
In Physics class, we were building parallel circuits, and as more lights were attached in parallel, they got brighter (as more power was being provided to the lights, and the resistance decreases). ...
2
votes
1answer
167 views
How much power can be drawn from stray electromagnetism in the atmosphere?
I know this probably varies quite a bit from place to place on earth. But just some rough estimates: if I were to pull power via multiple antennae tuned to a variety of different frequencies, how much ...
2
votes
2answers
202 views
Should the term Watt's Law be used?
I'm revising some electrical curriculum for a technical training program. In the curriculum students have to calculate values using Ohm's law and the equation Power = Current * Voltage (or P = IV).
...
2
votes
2answers
154 views
Can wireless power transfer harm organic life by anyway?
Now, humanity can beam 50-60 watts power through 10 centimeter-thick concrete block. Can such wireless power transfer harm us by anyways?
2
votes
1answer
59 views
Boiling water reactor
What are the typical power densities in conventional boiling water nuclear reactor per cubic centimeter of fission material?
2
votes
4answers
781 views
Do Alkaline batteries, NiMH, rechargeable alkaline, Lithium AA, all have similar MAX POWER?
So in physics, one smart teacher told me,
V = IR
or
I = V / R
but it is not always true, because ...
2
votes
2answers
106 views
Why do we need more power to do a job fast?
Let's assume we have two identical electric trains. One has a big electric motor (high power) and the other has small motor (low power). Let us assume the electric motors are of the same brand and ...
2
votes
1answer
173 views
Which speed can an electric scooter reach on a given slope?
Electric scooters are always "given" as "working with slopes up to xx%", but what does it mean?
Given motor torque and power, scooter+driver weight and wheels diameter, how can I determine at which ...
2
votes
1answer
76 views
What are the properties and impediments of a liquid air fueled engine?
I recently came across a very interesting article that suggested the possibility of using liquified gases like air, nitrogen, or oxygen as a power source for cars. It appears that this company is ...
2
votes
2answers
901 views
Total power consumption of electric device
For some electric devices, like a fan or air conditioner, I read about their power consumption in watts on their specification guide.
Does it tell about the power at normal or full speed? or Does the ...
2
votes
0answers
285 views
How much power to keep surface of aluminum plate at given temperature?
I want to heat one side of an aluminum plate enough to hold the other side of that plate $100K$ above ambient. I'm willing to assume that the heated side of the plate is "well" insulated (along with ...
1
vote
5answers
291 views
How do electrical devices suck electricity?
If the electric potential is 220V and some device needs 1500watts then how does it suck exactly that amount of electrical energy from outlet?
1
vote
4answers
757 views
Will Earth Hour do damage to power supply system?
There is always a debate around Earth Hour every year, and the opposite side of Earth Hour usually claims that
The (sudden) decrease and increase of the power usage in the start and end of Earth ...
1
vote
2answers
397 views
An Ideal Transformer
In a transformer assumed to be transformer, power in the primary is equal to power in the secondary. So in a sense, the power in the secondary is 'fixed'. Output voltage in the secondary is also fixed ...
1
vote
2answers
296 views
Calculate power $P=V \times I$
I have an adapter which mentions like this...
Input: 100-240V~1.8A
50-60hZ
So how much power does it really consume?
I just knew ...
1
vote
2answers
1k views
How do I calculate the power consumed by a lightbulb?
I'm studying a lightbulb and its variable resistance, given by the expression:
$R(T) = Ro[1 + α(T-T_0)]$, where $R_0$ is the resistance of the lamp at $T_0$.
In this case, $R$ is not given by Ohm's ...
1
vote
2answers
635 views
Does the 'mAh' rating of a battery have something to do with its power?
I'm curious about the 'mAh' of a battery: how can this impact the power of the battery?
I've done some research on the internet, and most of the articles I found explain about the 'amount of charge ...
1
vote
2answers
46 views
Light bulbs, Wattage meaning? [closed]
Light bulbs, Wattage meaning?
Two incandescent bulbs (120 V, 25 Watt) and (120 V, 500 Watt) connected to the same batteries.
Which one shines brighter? And why?
1
vote
2answers
182 views
Mechanics Question: Energy, Work and Power
I'm a pure mathematician by trade, and have been trying to teach myself A-level mechanics. (This is not homework, it is purely self-study.)
I've been working through the exercises and have come up ...
1
vote
1answer
67 views
is it possible to gain from charging cold battery
Is it possible to get higher load of energy into a battery if you charge it when its cold eg. +9C?
the battery is emptier, but does it let the power in?
Is it safe?
1
vote
2answers
315 views
Would a thinner atmosphere (such as high altitude) yield better solar panel energy generation?
I am curious. If you were to put a solar panel up in high altitude or on the surface of the moon, both of which have much less atmosphere to reflect/refract light, would that solar panel produce more ...
