Connect with us

Small Resistor Value - Question

Discussion in 'General Electronics Discussion' started by Stocky, Oct 7, 2016.

Scroll to continue with content
  1. Stocky

    Stocky

    1
    0
    Oct 7, 2016
    Hi everyone,

    I have a question about the voltage drop across a resistor with a small resistance i.e. <10 Ohms.

    My simple circuit to test this is a voltage source in series with a resistor. The resistor has a value of 4 ohms and is rated at 1W.

    If I set the voltage source to 1V I expect a 1V drop across the resistor. However with the 4 Ohm resistor the voltage drop is only 0.6V. If I use a 100 Ohm resistor instead it works as it should, a 1V drop.

    Can anyone please explain to me why this is happening?

    Thanks,
    Chris
     
    Last edited by a moderator: Oct 7, 2016
  2. davenn

    davenn Moderator

    13,617
    1,881
    Sep 5, 2009
    Hi there
    welcome to EP :)

    it may be measuring error with your meter

    what is the voltage source ?


    The other very significant possibility and the most likely cause, is that the 4Ω
    is loading down the PSU and causing a voltage drop on its output

    so with that in mind, were you using current limiting? if so, to what limit?


    Dave
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-