i don't get somethink about short circuits .i saw that a person can plug a wire with a carbon rod in some circuit to the wall output and the fuse did not blow and if i plug a wire in the wall output it instantly blows the fuse .Why his fuse does not flow and mine yes .Is it because my circuit has a low electrical resistance?

 

If you are not knowledgeable about electronics, DO NOT EXPERIMENT WITH MAINS VOLTAGE. YOU WILL ELECTROCUTE YOURSELF. Anyways, get a multimeter and measure the resistance of your carbon rod, and use the equation V=I*R to find the current going though it. You could try whatever you are doing with a low voltage power supply that can handle high currents. You can use some supercapaciators. However, too much voltage or reverse the polarity, and your cap explodes. You could do other stuff, but in general, short circuits are really dangerous. So you should really know what you are doing if you are going to attempt this. But in general, most power supplies cannot handle such high currents, and will trigger circuit breakers. Please do not do whatever you are planning to do. It is just very dangerous.

 

Thank you for that much-needed safety note, @marx the communist .

It would be much safer to perform experiments like that at much lower voltage using a transformer that has an isolated secondary. Are you able to find one?

Besides the electrical safety issues, there may be some risk of eye damage from the intense long-wave ultra violet that a carbon arc generates. Not my subject area but I found this:


Above is the spectrum of a carbon arc at the longwave end of the UV region.

This article provides additional information:

https://emedicine.medscape.com/article/799025-overview
https://emedicine.medscape.com/article/799025-overview
I think that the electrical safety issues are a more pressing concern at the moment, but once you get dead spots in your vision it can be very bothersome.

 

Why his fuse does not flow and mine yes .Is it because my circuit has a low electrical resistance?

Yes, the carbon rod has a higher resistance than the your piece of wire.