B Why is the test charge always positive?

AI Thread Summary
The discussion centers on the use of positive test charges in educational contexts, primarily for simplicity and consistency. While test charges can be either positive or negative, many educational resources opt for positive charges to minimize confusion for learners. Using a positive test charge allows for easier comparison of electric field effects without complicating the directional aspects of forces. This approach aids in teaching and helps students grasp fundamental concepts before introducing more complex scenarios. Overall, the preference for positive test charges is rooted in didactic considerations.
misbah alshaybani
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why test charge is always positive ?
 

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It isn't always positive. It generally has an arbitrary value, which can be positive or negative.
 
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.
 
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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