Why is the test charge always positive?

  • #1
misbah alshaybani
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why test charge is always positive ?
 

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  • #2
It isn't always positive. It generally has an arbitrary value, which can be positive or negative.
 
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  • #3
Could be your book/course uses always a positive test charge for consistency. The less changes in the system, the easier it is to compare the differences with the earlier cases, that makes teaching/learning easier.
 
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  • #4
Borek said:
Could be your book/course uses always a positive test charge for consistency.

I always use positive test charges when I teach, for simplicity. Negative test charge gives E vector in opposite direction than Coulomb force on it, which per se is not a problem, but you know, didactics :smile: When someone is learning about it for the first time it's better to avoid such things, we can come back to it later.
 
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