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Homework Help: Basic AS level Physics

  1. Feb 14, 2010 #1
    Calculate the mass of an ion that has a specific charge of 1.20x10^7 C kg^-1 and a negative charge of 3.2x10^-19 C.

    Textbook answer: 2.67x10^-26 kg.

    Question: if the ion has a negative charge of 3.2x10^-19, isn't that -3.2x10^-19?! In which case the answer would be -2.67x10^-26 kg?! Is the use of the word negative in this question a bit misleading?
     
  2. jcsd
  3. Feb 14, 2010 #2
    Hello Dan.West Ham supporter here(don't take the mickey).You make an interesting point.Specific charge is a ratio and I dont recall having seen it given either a positive or negative label.Thinking about it,it might seem to be more instructive to do so.
     
  4. Feb 14, 2010 #3
    Hi Dadface, it isn't actually the specific charge I'm concerned about, its the charge of the ion. Is 'a negative charge of 3.2x10^-19 C' the same as -3.2x10^-19 C?! In which case the answer would be -2.67x10^-26 kg?! Is the use of the word negative in this question just a bit misleading?

    Thanks very much!

    P.s. Just watching the Bolton game myself!
     
  5. Feb 14, 2010 #4
    Yes it is the same and it is twice the charge of the electron.From its charge and mass it looks like it's an oxygen ion.
     
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