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Electrostatic Force problems

  • #1
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So there was a question in a textbook that went as so:

'Two point charges (30 cm apart in air) are charged by transferring electrons from one point to another. Calculate how many electrons must be transferred so that an attractive force of 1 N exists.'

It is assumed that both point charges are the same. It was calculated that the charge of each point charge is approximately 3.16 * 10^-06 C. Then this value was divided by the charge of an electron to get the number of electrons transferred. This was the correct answer

However, i do not understand why dividing the charge of the point charge by the charge of an electron gives the amount of electrons transferred. I cannot get around this concept. It would be great if some could walk me through exactly why this is the case.
 

Answers and Replies

  • #2
Orodruin
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The number of charge carriers transferred must be the total charge divided by the charge per charge carrier. In this case the charge carriers are electrons.
 
  • #3
Sorry, but i do not understand what a charge carrier is.
I am only in year 12. Could you please explain further. Thank you very much
 
  • #4
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(Number of electrons) x (the charge of one electron) = (Total charge)
When you know two of the variables, you can find the third using algebra.
 
  • #5
kuruman
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However, i do not understand why dividing the charge of the point charge by the charge of an electron gives the amount of electrons transferred. I cannot get around this concept. It would be great if some could walk me through exactly why this is the case.
The concept that you mentioned is general and applicable to cases beyond charges, it involves elementary division and is taught by year 3 in most schools. It is the same concept as the one needed to solve the following problem: Jimmy sold apples at $0.20 each and collected $1.80. How many apples did Jimmy sell?

Instead of apples think electrons and instead of dollars per apple think Coulombs per electron.
 

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