what's the difference between test charge and point charge

Asked by  | 22nd Jul, 2011, 12:00: AM

Expert Answer:

Test charge and point charge are synonymous in the sense that both are unit positive charges. However, conceptually. a point charge is the one with dimensions so much smaller than the other dimensions appearing in the problem so that they can be ignored; while a test charge is the one which is used to test the effect of an electric field.
 
The test charge is imagined to be so small that it does not change the charge configurations causing the fields it is measuring. Generally this charge has to be small enough that it would be considered point like, but technically it is the charge that must be small, not necessarily its dimensions.

Answered by  | 22nd Jul, 2011, 12:19: PM

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