In thinking more about this, it makes sense that just as capacitor noise is a voltage in the open circuit condition, inductors should have current noise in the short circuit condition. This will apply even for zero resistance as it's just the electrons randomly sloshing back and forth at...
Capacitors do have thermal noise, see for instance the wikipedia article for Johnson-Nyquist noise. By the same reasoning so will an inductor.
In the case of an inductor, yes there is series resistance, but I'm interested in the noise associated with the inductance alone.
Homework Statement
Although it's easy to find calculations of thermal noise for resistors and capacitors, the equivalent for inductors is not found. What is the relevant formula? Is there some simple conversion for this?
Homework EquationsThe Attempt at a Solution
We seem to have come full circle. Here I return to the question in my first reply: "If the tangential DC field is real, then how does it arise?" If it is real, surely it will impart motive force on a test charge. For instance, DC electrostatic fields are notorious for dust collection via this...
Now we fully agree. By extension, there also cannot be a current-driven DC E-field parallel to an infinitely long straight wire, which is just a loop that has reached the zero curvature limit. In a circuit with discrete voltage sources and folded current paths, there will always be E-fields...
We ARE talking about a closed loop E-field. If there is a tangential E-field outside of the conductor, it is required by the circular geometry of the loop. I agree totally that those arise only in time-varying situations. That's the whole point - you cannot have one at DC! Again, electrostatic...
So you are saying that a free standing, closed loop E-field is incapable of inducing other than electrostatic equilibrium? Speaking as a magnetics designer, I'm not sure you follow the transformer analogy. Closed loop E-fields most definitely induce voltage in and drive current through wires...
That is not an entirely satisfactory answer. All you are saying is that an open circuit wire has zero current once the stray capacitance has charged up. However, if the tangential field is real, the voltage induced in a wire parallel to it should be both measurable and able to drive continuous...
Homework Statement
Discussions of the possibility of a tangential E-field external to a current-carrying conductor must include a voltage source and a return path. Here the problem is reduced to (we believe) the simplest possible geometry. Assume that a circular conducting loop has constant...
Background: an ordinary wire supports an external radial electric field proportional to voltage, and an internal axial field equal to current times resistance per unit length. The present question is whether the internal axial field has an external counterpart. The original question that...
Even if the rocket traveled "straight up", the surface of the Earth is turning, which carries the observer away from the origin of the trajectory. In this respect, it is the observer who moves horizontally with respect to the rocket rather than the other way around. To this visual effect, add...
You should be able to model it as two stacked single gate fets. That's really all it is inside, sharing one channel so the drain of the lower one is also the source of the upper one. Set Vthresh for the upper one equal to the difference between the external lower and upper gate thresholds.
That's one working configuration, but the electromagnets used in scrapyards use a better design that you can look up. It's a circular center pole surrounded by a circular outer pole. These can use solid steel because it uses DC current and eddy currents are transient at magnet turn on and turn...
Galvanometer? That is a totally obsolete instrument!
Suffice to say, if two identical voltmeters are connected in series across 100V, each will individually read 50V.