Recent content by lesaid

Thanks for the replies! I am indeed! But before getting into that, I'd like to check my understanding of the geometry of the system with and without the central mass! If we remove the 'heavy mass' for a minute and just think about the rings and spokes - I was envisaging that all the spokes...

A thought experiment. Two rigid, concentric rings, joined together by a series of lightweight elastic radial spokes. These rings and a heavy mass are approaching each other, such that in the frame of the rings, the mass is traveling along the central, perpendicular axis and will pass through the...

Thanks for posting that article. I shall enjoy reading it! And great that you are keen to investigate physics at home. I too enjoy home experimentation in 'practical' physics (have a thread about a Foucault pendulum in the 'projects' area of this forum). It is a great way to learn! Looking...

Off hand, I really don't know how much such a coating would influence the capacitance. But I would guess, not by a lot. It's something I'm now interested in figuring out, though I haven't got time at the moment! Can you share with us what you are trying to achieve here? I have the impression...

Yes, or have a grounded conductor nearby, so the sphere is no longer isolated. If you want to make a capacitor, an isolated sphere is perhaps not the most effective way! I don't know how effective coating the sphere would be. I am sure it would raise the capacitance, but I haven't tried to...

I think you might be mixing up "relative permittivity' with 'absolute permittivity'. The relative permittivity of vacuum, and to a close approximation, air, is indeed (by definition) '1'. However, the capacitance formula calls for the absolute permittivity. Take a look at...

You have the correct formula for the capacitance of an isolated sphere - i.e. ##C=4\pi\varepsilon_0 R##. Plug in the following values ##\varepsilon_0=8.85\times 10^{-12} F m^{-1}## (the 'permittivity of free space') ##R=0.1 m## This comes out to ##1.11\times 10^{-11} Farads## or...

It may be interesting to know that the Earth itself as an isolated sphere has a capacitance of about 710 uF. Whereas the sun is around 77,000 uF and a 10 cm sphere would be around 11 pF.

No - it is the air around the sphere, the moisture in that air, anything other insulator near the sphere will contribute to the dialectric. I believe that, for example, humid air around the sphere would result in a slightly higher capacitance than dry air, Though I stand to be corrected in that...

An 'ordinary' capacitor generally consists of two electrodes very close together separated by a dialectric. The actual capacitance is dominated by the geometry of those components and the material of the dialectric. Whatever is around that capacitor has little effect in comparison. However, an...

The sphere would still have capacitance, but so would whatever was connected to it, both between the connected 'thing' and the sphere, and between the connected 'thing' and the surrounding environment. So the measured capacitance is influenced by the measuring device. In my suggestion, when...

Just to sound a note of caution. A 60 cm sphere, by my calculations, if at a guess, it achieves say 500kV, will store over 4 joules (capacitance 33 pF). If it achieved 800 kV, that would be around 10 joules. If my quick calculation is right, this is verging on what I believe to be dangerous...

Just discovered the recent posts here! I've been away from this project for some months (studying other things) and will be returning to continue my efforts some time in June or July. In the meantime, I am happy to exchange ideas and experiences with others engaged in the same kind of thing...

How about taking two identical conducting spheres, well separated. Connect each one individually to a known voltage relative to an 'absolute ground'. Not an arbitrary reference, but a ground where the numbers of positive and negative charges are equal. Each sphere will take on a charge...

Just did some calculations. If I'm correct, and assuming a spherical bearing fitting inside a spherical 'container' with a galinstan fluid, the inner hemi-spherical piece would need to have a radius around 6 cm (to support up to 2 kg (the bob plus the shaft and pivot cage assembly). A diameter...