Recent content by mendes

I think I found the answer: Wikipedia: http://en.wikipedia.org/wiki/Insulator_%28electricity%29 Dirt, pollution, salt, and particularly water on the surface of a high voltage insulator can create a conductive path across it, causing leakage currents and flashovers. The flashover voltage can...

Have a look at this: http://3.imimg.com/data3/TE/AF/MY-5753/porcelain-bushing-for-transformer-rectifier-250x250.jpg

Hello, I would like to understand why "bushings" that are used as insulation for high power electric cables in transformers, and which are often made out of porcelain or glass, I would like to understand why they have this form of "skirts" ? Why aren't they just as a simple cylinder?

Its quite simple actually, the suspension is used in magnetic particle testing. The magnetic powder is needed in a liquid carrier (kerosene or sometimes water). A magnetic field is applied on the metallic part that is to be inspected against flaws, and the suspension dropped on the part. The...

The dielectric constant of iron oxide is around 1 (very low), quite similar to the one of kerosene. I thought about using a simple capacitor to measure the powder concentration, as it is usually done in moisture meters (water dielectric constant is high (80), is quite different from the one of...

Many thanks for the detailed reply. In terms of capacitance because kerosene and iron oxide (powder) have very similar dielectric constants, this property can not be used to measure the powder concentration, I think. So, if we use the inductance based principle we do not expect a considerable...

Thanks for your answer. I would like to have a link on how the tank circuit is used to measure the dielectric constant of liquid in die-sinking EDM. Some time ago I used a tube with mixed kerozene and powder that I inserted in a coil to see if it changes its inductance but there was no...

Hello, I am looking for a way to measure the dosage of a powder (made of metallic particles (ferromagnetic) that are 6 microns large) in a liquid solution that is kerozene. When mixed with the liquid a suspension is obtained that takes about one hour for the powder to settle down. Once...

Ok, but how could we understand the fact that the orbital momentum is zero ?

Hello, When the azimutal quantum number l = 0, for the s-orbital, the orbital momentum itself is 0, as it is proportional to l(l+1), so how can we understand this ? Is the electron not orbiting around the nucleu or what ? :) Thanks

Hi all, In a compensated n-type semiconductor where there are both acceptors and donors in similar densities, the acceptors are filled with electrons (and therefore have a negative charge) even at very low temperature, close to 0 K. Where do they get these electrons from ? Whether...

Hi all, I would like to understand the mechanism by which a neutral impurity can bind an exciton. Because the impurity is neutral the attracation can not be simply electrostatic. I know that there must be a "neutralising electyron (or hole)" in the machanism but things are not clear enough...

I would like to understand what is "exchange splitting" in atomic orbitals. For which orbitals does it happen ? Is there any similarity between this phenomenon and the Zeeman effect (which breaks the degeneracy on the magnetic quantum number and then splits the orbital into sub-orbitals having...

When we provide thermally or optically en energy higher than the semiconductor bandgap we create elctron-hole pairs, that is electrons are extracted to the valance band and they become free to move inside the crystal. My question is: are the semiconductor atoms then ionized, which means for...

The base is a separate unit (from the handset charger) and has a separate power supply.