It seems that a core-less dynamo would have a maximum efficiency of 2.
The argument is as follows:
JxB emf= E.J emf
JxB does no work
E.J does work
Thus output is twice the mechanical energy spent
Inward Poynting vector?
It seems that to get 10K drop in a 1L small cylinder it needs to have area of 6m^2.
About the large cylinder, to be able to do sufficient heat exchange area can be similar.
Note that "everything" is isothermal except the compression.
So it is outputting air hotter than the environment, while...
I do get net work with adiabatic compression, but only if the large cylinder is kept under environment temperature during the fill phase. If the heat is left to build up freely, negative work done.
It is relatively inefficient with 60L large cylinder and 1L small.
To make it efficient a gas...
When deriving the Maxwell Stress tensor, the Lorentz formula is converted from point particle:
F=qE+qv x B
Into current and charge density:
F=ρ E + j x B
However an argument can be made that we can't "fieldify" both q and E at one step, and thus, a "coercion" of the field to a value is...
Lets say we got a larger cylinder-piston combo and a smaller one.
First we move the larger cylinder, filling in with vacuum. Then we pump in air, using the smaller cylinder, isothermally, with variable expansion ratio.
Here, we clearly have exp ratio > P_atm/P_final
We then compress the larger...
The counter-example is as follows: We have a rectangular toroid ferrite(ring ferrite), magnetized in a closed loop around the ring. We put capacitor plates on top and bottom surfaces, with suitable direction. Now the Poynting vector points inwards or outwards. We look at a cylindrical surface...
I have seen shadows of clouds over the sea. What could be the explanation? Let me explain why there needs to be an explanation:
Radius of sun: ~600000km
Distance to sun: ~150000000km
(assumed) distance to cloud: 2km
This means that there should be a 16 metre edge around the shadow where the...
I guess I'll have to jiggle Copper ions. Jiggling bosons might be as good as creating/destroying them for my purposes. Maybe if I wrap a roll of Aluminium foil with paper and attach it to mobile phone antenna it'll be good enough. Don't know whether to also include "ground" foil roll. All in...
Basically what I need is lots of bosons created for a very short time and then turn into fermions. I presumed, if I do electrolysis of sodium bicarbonate, that sodium atoms would be produced at the cathode as an intermediate product, before reacting with water and producing hydrogen.
If we do electrolysis, using a potassium electrolyte in water, the Na+ ions turn into Na atoms at the cathode. The question is, how long, on average, will it take for the Na atom to react with water and form a Na+ ion again?
If we switch a super-conductor between normal and Meissner states, using varying magnetic field, there has to be some delay from when the field exceeds the critical field to the appearance of Meissner state. Have there been any experimental measurements of this delay? What are the measured values?
It is claimed that QED could predict certain quantities, like the lamb shift and magnetic moment of electron with astonishing precision of 12 digits. My question is the following: does QED predict only a few things to this precision, or does it predict, this precisely, the entire arbitrary...
Second London Equation, which is supposed to represent the current in a superconductor. (SI units)
∇×j=-(ns e2/m) B.
Lets have a look at a super-conducting wire. The magnetic field is:
B=μ0Ir/(2πr)
Where Ir is the current enclosed by the radius r.
We are talking about the current at some depth...