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Voltage Drops In a Circuit

  • 02-12-2003 08:16PM
    #1
    Pacifico
    Closed Accounts Posts: 5,114 ✭✭✭


    Hey, just wonderin' if someone can enlighten me here.

    In a lab a college if you have to measure a voltage drop accross a resistor can you just uses a DMM and connect it accross the two legs of the resistor?? is that all you have to do?

    Thanks in advance, Alex.


Comments

  • #2
    daveirl
    Closed Accounts Posts: 14,483 ✭✭✭✭daveirl


    This post has been deleted.


  • #3
    Pacifico
    Closed Accounts Posts: 5,114 ✭✭✭Pacifico


    thanks:D :D


  • #4
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 98,142 Mod ✭✭✭✭Capt'n Midnight


    I think you are supposed to take into account the resistance of the DMM - if the resistor is in the MegaOhms area then the DMM resistance will matter - if it's in the order of a few 10's of K's then it will be negligable.


  • #5
    daveirl
    Closed Accounts Posts: 14,483 ✭✭✭✭daveirl


    This post has been deleted.


  • #6
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 98,142 Mod ✭✭✭✭Capt'n Midnight


    20 Mega Ohms is not infinite

    To be pedantic I have at home a 10 GigaOhm resistor - tolerance is 10% (a real curiousity) it is in a sealed glass vial with leads coming out the ends.


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  • #7
    Jaden
    Registered Users, Registered Users 2 Posts: 2,394 ✭✭✭Jaden


    Anyone who has an unused 10 gigaohm resistor at home, and bothers posting about it on an Internet bulletin board is obviously not just pedantic, but also a beardy nerd who needs some friends and/or more contacts with the opposite sex.

    :)

    The opinion that most DMMs are designed to compensate for measurements by having near infinite input resistance is correct, and would only be poo-pooed by someone more anally retentive than Rimmer from Red Dwarf.

    It's Friday, lighten up.


  • #8
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 98,142 Mod ✭✭✭✭Capt'n Midnight


    Originally posted by Jaden
    It's Friday, lighten up.
    eh Bud ?
    I posted on Thursday
    Anyway on the 200mV range older DMM's might only have a 200K input resistance !

    PS. Anyone want to buy an Unused Hermathecially Sealed Open Circuit ???


  • #9
    daveirl
    Closed Accounts Posts: 14,483 ✭✭✭✭daveirl


    This post has been deleted.


  • #10
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 98,142 Mod ✭✭✭✭Capt'n Midnight


    Originally posted by daveirl
    And whats the usage of a 10G resistor anyways?
    The perfect present for the person who has everything.... :)

    For practical purposes a DMM is infinite - but in a college lab you maybe have to take into account the theory..


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