1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I Confused about electrostatic voltage and DC voltage

  1. May 8, 2016 #1
    Hi everyone,

    I am a little confused conceptually about electrostatic voltage and DC voltage. I did my bachelors in biochemistry (where I’m working today), I’m learning/relearning physics as a hobby. I did well in high school physics and first year physics but I’m afraid I’ve forgotten most of it. Just want to say sorry about the length of this post, I’m trying to get this all straight in my head.

    So I’m pretty sure I understand how a van de Graaff generator makes a voltage, it accumulates electrons on a metal dome and that concentration of charge makes an electric field. A charged body within that electric field at a given position will experience a force (either attractive or repulsive, depending) and the charged body is moved by that force until it can’t move any more. The distance moved multiplied by the force is the energy required (aka. work done). So a stationary charged body at a given position (e.g. it’s held in place with glue) will have a potential energy, which is the voltage. Please correct me if anything I wrote above is wrong.

    I am confused conceptually about the following. If I have a DC power supply, and I connect the positive terminal to one metal dome and the negative terminal to another metal dome (and it’s all isolated from ground), then I turn on the power supply, will the metal domes accumulate positive/negative charge much like a van de Graaff generator? I assume it will, but I find it hard to conceptualize.

    For example, I saw these boost converters that claim to turn a 5V input to a 100 kV output. I find it hard to believe that if I connect a metal dome to the positive terminal and another metal dome to the negative terminal that a 100 kV potential will build up between the domes. But then again I’m not sure what would happen….

    Thanks in advance.
  2. jcsd
  3. May 9, 2016 #2


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    hi there
    welcome to PF :smile:

    any metal plates domes, bits of wire connected to the terminals of a battery or other PSU will come up to the voltage of that PSU 12V 50V whatever the supply is

    why hard to believe ? if using one of those voltage multipliers then yes that will be that 100kV voltage difference between the 2 domes
    what would you otherwise expect to happen ? :smile:

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted