Montag, 18. Juli 2011

Current and the crazy world of electronics

Hi again my dear followers ^^

Sorry that i didnt wrote something in the last few days. My 300 € Mainboard just gave up. Looks like a little SMD-Resistor burned through. Just a few weeks after my garantee canceled. Accident?
I once heard a rumor that things like a vacuum cleaner are build to break a few weeks/month after the garantee canceled so you have to buy a new one. It would be easy to take some components that have a reduced lifespan.
So now i have a laptop till next month when i get my salary to buy myself a new mainboard and if the worst case comes my CPU may have died to.

But enough of my problems with computer hardware. Im here to tell you about current after i told you last time about voltage.
We remember:
Voltage is not real. It's just a unit. But current is real. Real enough to kill you if you get to much. Current has the unit Ampere and describes the flow of electrons through a medium.
Physic-basics 1:
- Electrons are negative loaded
- unequal loaded poles attract each other

So, now we understand why the current flows from the - pole to the + pole. To make each pole equal. Thats also the reason why batteries can be unloaded.
Technically the current flows from the - pole to the + pole but on all blueprints its from the + pole to the - pole. Thats because as the current was discorvered the "electricans" fucked some things up and made some rules which were false. After they had discovered their mistake it was to late and they said "wayne, lets keep it like this."

So if you lick at a 12V battery, your tonuge conects the + pole and the -pole. Theoreticaly your body has a resistance between your hand and your feet of 1000 Ohm. In the reality its way more (most times around 2.000.000 Ohm and more) but the people who had to work out safety-rules had to assume a worst case senario like you are standing in the rain, barefoot on wet earth and your skin is soggy that your body resistance is lowered.
So your tonuge is connecting the 2 poles and current can flow.
Lets calculate:
We want to know how much current flows. So we take the formula:
I (Ampere) = U (Voltage) / R (Resistance)
I = 12 V / 1000 Ohm
I = 12mA
So,  if you have no skin and would touch a 12 V battery, then you may already have problems to let the battery go.
Good to know:
The human body signals work with 0,000000000004 - 0,008 Ampere (wide range, i know but its good to not feel every signal your brain gives to your bodyparts) and your body withstands around 0,05 Ampere ( 50mA) before you are risking serious inner burnings.

Now you know about the risks with electronics. Next time:
resistance, frequenzy and some new formulas.
Bye :D


  1. Very interesting, it's quite some time ago I had this stuff in school.

  2. But electricity is so fun to play with.

  3. Wow that really refreshed my memory, makes me want to lick a battery now, haha. following+

  4. If i keep reading this blog, by year's end i will be a certified electrician hahahah

  5. Why do I have the urge to lick a battery ...

  6. No accident there, mate.
    I'm a mechanical engineering student and one of the first things I was thought was something that I could loosely translate with "marginal engineering".
    To make it really simple, stuff really is built to last just a bit longer than the guarantee lasts.

    Anyhow, following and supporting! :)

  7. At least it gives you an excuse to invest in new things, right?

  8. Sorry to hear about your mobo :(

  9. It's like I'm back in high school sitting through chem class haha.

  10. Hve learnd all that stuff 2 years ago ,electricity is awesome

  11. I really hate it when stuff breaks and you have to buy a new one, when stuff from like the 50s is still around now.

  12. today's tech is only good for like 2 years before they expect you to buy something new.