All Questions
Tagged with electricity thermodynamics
152 questions
4
votes
4
answers
558
views
Does a packed fridge cost the same as an an empty fridge? (Electricity cost) [duplicate]
Discounting initial power to bring an item into a frozen state, then is the electricity cheaper to leave my fridge empty; or is the cost the same for it being packed with frozen foods?
If my fridge is ...
- 101
0
votes
2
answers
84
views
Could you make a fire torch with electricity? [closed]
Similar to a blowtorch, is there a way to generate a flame without using gas or liquid fuel(like butane, propane, etc)?
(source)
For example I'm thinking about those portable air heaters, could one ...
- 193
2
votes
1
answer
92
views
Gibbs phase rule argument about battery voltage dependency on the state of charge
I'm studying battery physics, particularly the dynamics of full discharge, and I am having trouble understanding an argument that is based on the Gibbs phase rule
$$F=C-P+2.$$
I understand the phase ...
- 1,018
0
votes
1
answer
32
views
Heating a Material with Negative temperature coefficient of resistance
TCR (Temperature Coefficient of Resistance): $R = R_0[1 + α(T - T₀)]$ Where: $R$ is the resistance at temperature $T$, $R_0$ is the resistance at a reference temperature $T_0$, $\alpha$ is the TCR of ...
1
vote
3
answers
122
views
Electrical energy is $I^2Rt$, and heat dissipated is also $I^2Rt$?
My book says:
Let a current $I$ be flowing through a conductor of resistance $R$ for a time $t$, when a source of potential difference $V$ is connected across its ends.
Then, it proceeds to prove ...
- 143
0
votes
1
answer
104
views
Why should the heating coil of a heater have high resistance?
In my book, it is given:
The resistivity of an alloy is generally higher than that of its constituent metals. Alloys do not oxidise (burn) readily at high temperatures. For this reason, they are ...
- 1,096
0
votes
1
answer
182
views
How does the rise in temperature of fuse wire depend upon its radius?
The question could be understood as if we have two fuse wires one of current rating 1 A and one of current rating 8A then what should be the ratio of their radius?
I tried the following:
We know, $Q =...
- 107
0
votes
1
answer
59
views
Fuel Cell Operating Pressure
I have seen anecdotal testing of fuel cell stacks. Intended to demonstrate that their power output can be improved through the addition of a centrifugal blower.
What are the limits associated with ...
2
votes
1
answer
188
views
What can cause a spot above my WiFi router's antenna? [closed]
Lately a weird dark spot has appeared right above the antenna of my wifi router. It wasn't there before.
I have tried to wipe it and it got a little bit brighter but I don't think it's dust.
My guess ...
- 21
1
vote
0
answers
55
views
Using the electrolysis of water to cool a room [closed]
Browsing the internet today I came across this very esoteric paper which purports to describe the construction of a device which uses the electrolysis of water into hydrogen and oxygen (a highly ...
- 531
0
votes
1
answer
21
views
Heating Effect of Current wrt Transformers
I just learnt that we use step up transformers to reduce heating losses in overhead wires. I was given some values.
Say, the power plant is a 1 million watt rated plant.
The voltage is $400V$ at the ...
- 81
2
votes
1
answer
357
views
How much electricity can be directly generated from air humidity?
There have been some recent papers on harvesting electrical energy from air humidity using nanoengineered materials:
"Power generation from ambient humidity using protein nanowires" in ...
- 13.2k
0
votes
2
answers
422
views
Making energy out of freezing ice
Just a thought from a dream
Since water expands so greatly when frozen could it be possible to freeze the water in a metal cylinder but one side is like a car piston with a very high gear ratio which ...
- 11
0
votes
1
answer
25
views
How to boil 40ml of water using a solar panel of 15v and 1amp? [closed]
I am making an application to use in third world countries where there is unlimited sunshine
I need to boile a very small amount of water, up to 40ml, using a solar panel that generates 15v and up to ...
- 11
1
vote
0
answers
32
views
Electric Furnace Temperature Theory [closed]
I am designing a small melting furnace using 120VAC with an ideal maximum current of 10A. I'll be using Kanthal A-1 resistance ...
- 111
3
votes
2
answers
159
views
Should I put my freezer in the middle of the living room? [duplicate]
There is a freezer in my kitchen. It has frozen fish fingers and spinach and potato waffles and leftovers. The food stays below freezing temperature using the principle of latent heat. The freezer ...
- 319
1
vote
2
answers
182
views
If charged particles have Brownian motion, would this motion be associated with (or produce) heat or electricity?
If we have charged particles having Brownian motion, would this motion be associated with (or produce) heat or electricity? Would it produce electromagnetic radiation (and if it would produce it, what ...
- 2,878
19
votes
6
answers
8k
views
Is there a liquid which boils at room temperature and normal pressure, and can we use it to produce electricity?
In many places the temperature difference between day and night is more than 20 degrees C. Max 45 C and min 25C. Can we create a machine which uses a liquid which has boiling point around 25-30 C and ...
- 293
0
votes
1
answer
36
views
Does passing an electric current along a strip of metal submerged in saltwater cause anything?
If saltwater corrodes metal.
Can we effectively stop this by passing some electric current?
Has this been tried before?
0
votes
1
answer
166
views
Would a grounded copper heat sink located near a room's ceiling be an effective way to reduce a room's temperature?
I am thinking about a cheap but effective way to reduce the temperature of my bedroom in my apartment during hot summer nights. I live in an old apartment building and the air conditioner located in ...
user300400
3
votes
6
answers
1k
views
Help me understand the physics of electrical heaters and their efficiency
I was having a conversation with my friend the other day. For a bit of background, I know next to nothing about physics, and he took physics lessons as part of his study to become an electrician ...
- 31
3
votes
3
answers
11k
views
Watt & heat calculation
this is my first post in this forum. Unfortunately, I'm not very familiar with physics and I hope I'm in the right place here. I asked myself how much energy I need to heat something.
I've found that ...
- 133
2
votes
4
answers
524
views
Do electrical appliances reduce the heating bill?
When you use an electrical appliance, most of the electricity used is turned into heat. Will the energy cost of using something like an iron be subtracted from the heating bill making it effectively ...
0
votes
2
answers
201
views
Efficiency of electric heaters
I was reading this question. A person was asking what is the efficiency of an electric heater, and to sum up, people were answering "All resistive heating, can be considered to have 100% ...
5
votes
2
answers
1k
views
Is there a theoretical efficiency limit for thermoelectric generators?
Typical Thermoelectric/Seebeck generators operate at 5-8% efficiency.
Is there an upper limit to the conversion of heat flux (temperature differences) directly into electrical energy?
- 387
1
vote
0
answers
90
views
Anyone know what this physics lab equipment, found in the storage room, are? A resistivity kit or an optic bench? Any ideas? No identifying brand seen
1.
2.
3.
4.
5.
6.
7.
8.
These equipment were found in the physics storage room. Unsure of how old they are or of their usage. They might be part of a resistivity kit or some sort of optic bench. Any ...
1
vote
1
answer
221
views
Is it possible to make water steam batteries?
I have a few questions,
What happens if we compress water steam?
Does its temperature increase (Gay-Lussac’s law)?
Or does it become liquid?
Can we store the compressed water steam in a tank and use ...
- 121
0
votes
0
answers
18
views
Do heat-producing facilities recycle byproduct heat into their energy consumption?
Consider a steel mill or an ore smelting facility, what do they do with the heat they produce? On a consumer scale, heat pumps are a thing for decades (e.g. fridges), would this not be a feasible ...
- 3
0
votes
0
answers
67
views
Electromotive force in terms of thermodynamics / statistical physics
I would like to understand how electromotive force arises in terms of thermodynamics/ statistical physics. It seems like a rather simple question, but my (admittedly brief) search hasn't produced ...
- 65k
2
votes
1
answer
398
views
Formula for Temperature Gradient due to Joule Heating [closed]
I was wondering how to calculate how much the temperature will increase in a cylindrical wire due to current passing through it, I did some googling didn't find anything so I came up with the ...
- 165
0
votes
1
answer
253
views
Heat dissipated by resistor formula question
The heat dissipated by a resistor is given by the formula
$$ I^2 R $$
Any circuit portion has an equivalent resistance. Does that mean that the heat dissipated by any circuit portion, doesn't matter ...
- 15
12
votes
3
answers
2k
views
Why do two heaters with the same power produce different heat?
I have two portable electric heaters and their power is exactly the same: 2000W. One is using ceramic technology, and the other resistor technology. The one with ceramic technology produce a lot more ...
- 237
0
votes
1
answer
104
views
Constant Temperature in Conductive Wire
I know that when an electric current flows through a conductor, it produces heat. However, while working on some questions, I came across some statements assuming that the temperature is constant. ...
- 67
0
votes
2
answers
41
views
Why isn't steam turbine condensation carried out in spare boilers? [closed]
Why do steam turbines at the power plants have to transfer heat to the environment or to so-called cooling towers? Why not reject the heat through tubes carrying the steam into another boiler (...
- 350
0
votes
2
answers
63
views
Cutting down on power by bypassing mechanical to electrical conversions: Why not? [closed]
The only answer to this I can think of is energy portability issues.
Another modern-world insanity is converting mechanical energy to electrical, only to turn it back into mechanical. The example I ...
- 350
5
votes
1
answer
4k
views
How does cold make batteries drain faster yet simultaneously they should be refrigerated to keep a charge?
I have always known via common knowledge that batteries drain quicker when it's cold. I've been told it's best to keep them in an inner pocket close to body heat when outdoors (e.g., batteries for ...
- 249
8
votes
3
answers
2k
views
Why do metals conduct electricity faster than heat?
I have read this question:
https://physics.stackexchange.com/a/561125/132371
where cuevobat says:
You will note if you examine the tables on conductors that some metals that are good electrical ...
- 29.3k
0
votes
0
answers
232
views
Would it be possible for superconductors to work using the coldness of space?
Some temperatures and numbers to work with... The baseline temperature of outer space, as set by the background radiation from the Big Bang, is 2.7 K (−270.45 °C; −454.81 °F)
The temperatures for ...
0
votes
1
answer
173
views
My crazy superconductor idea
I watched a television documentary on superconductors. The summary was that in a ring of neodymium magnets, the superconductor would spin around on top of them levitating whilst it was frozen with ...
- 117
3
votes
2
answers
363
views
How is excess grid power dissipated? [closed]
I know that power/electricity generated (from conventional power plants or renewables) is generally instantaneously consumed, with grid operators constantly ramping generation to equal demand. My ...
- 460
2
votes
0
answers
145
views
How can graphene at thermal equilibrium induce current?
This research from the University of Arkansas claims to harvest electrical energy from thermal vibrations in a sheet of graphene:
The idea of harvesting energy from graphene is controversial because ...
- 2,772
1
vote
3
answers
198
views
Contradiction in heating effect of electric current
I am a tenth grade student.
Actually I have two questions.
I read that internal resistance of a cell decreases if the temperature of the electrolyte increases.
But isn't it contradicting what is said ...
- 21
0
votes
1
answer
39
views
Does electromagnet work without heat of wire?
If we isolate wire with thin wire and assuming that no heat rejected by wire then does electromagnet work. If it work then it violate conservation of energy .
1
vote
0
answers
127
views
Why do we use nichrome if heat is inversely proportional to resistance at constant voltage?
Why do we use nichrome in heating appliances? I've been listening that it offers higher resistance and hence, should generate more heat; as governed by $H=i^2Rt$. But, shouldn't we be using heating ...
- 11
1
vote
2
answers
184
views
Electrical noise on a waveguide and Johnson-Nyquist spectral density noise
In his 1928 paper, Nyquist derives the famous Johnson-Nyquist noise relation which gives the voltage fluctuations around a resistor at thermal equilibrium.
To show it, he starts to consider two ...
- 1,560
2
votes
1
answer
2k
views
Clean and simple derivation of Johnson Nyquist noise
I am not sure to get the derivation of Johnson Nyquist noise. I would like to understand it under black-body radiation approach.
Consider this reference: http://www.pas.rochester.edu/~dmw/ast203/...
- 1,560
0
votes
1
answer
201
views
Does fire caught by appliances causes short circuit [closed]
I know that short-circuit causes appliances to catch fire.But in my exam question was does the assertion is true
I think although each of wire has insulation but they are separated by a distance at ...
- 178
9
votes
8
answers
5k
views
Clarification of the concept "less resistance means less heating" in a wire
So my textbook says that the reason cables that are suppose to carry high currents, are thicker that those that are meant to carry lesser current, is that "less resistance (of the wire) means less ...
- 350
1
vote
2
answers
2k
views
Nickel plated steel strip for li-ion Battery pack - Purpose of Nickel Plating?
I am trying to build a battery pack from 18650 batteries, each interconnection is made from steel strip, most '18650 strip' has a steel core with nickel plating.
I have a question regarding the ...
0
votes
1
answer
85
views
Electrochemistry heat generation
In electrochemistry the Nernst equation says Gibbs=-nFE and the reversible heat=TdS= T*partialE partialT * -nF but the Bernardi heat equation is q= I(Voc-V+TpartialE partialT) when we know that the ...
- 861