Question

Two point charges -20 C and 40 C are placed r distance apart, then potential due to these charges will be zero in ?

Answer 1

@Vincent-Lyon.Fr

Answer 2

How to mathematically show that the potential will be zero in region A and B ?

Answer 3

You need to be twice as far away from the 40 C charge as from the -20 C charge.
It is not possible in region C where the first former distance is always smaller than the latter.

Actually, in the plane, the solution will be given by two hyperbolas.

Answer 4

Actually i want to know how u deduced the above conclusion ?

Answer 5

This one

You need to be twice as far away from the 40 C charge as from the -20 C charge.

Answer 6

Like this,

\(\large \sf \frac{k\times40}{r}=\frac{k\times20}{d}\\ --> r=2d\)
??

Answer 7

Oh so what you wr trying to say that null point will always be closer to the smaller charge i.e -20C. In the region C any point will be closer to the 40C charge and farther from the -20C charge..?

Answer 8

Yes!
\(V=\large k\frac{q_1}{r_1}+k \frac{q_2}{r_2}\)

Answer 9

yeah..yeah...i got it now !

Thank you very much sir !
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