Zero Potential and Zero Field
Zero Potential and Zero Field
- Zero potential and zero resultant field are different conditions. One uses signed scalars; the other uses vectors.
Zero potential is not zero field
Total potential is zero
Opposite-sign scalar potentials can cancel.
Resultant field is zero
Same-sign charges can produce opposing field vectors between them.
- A point between two charges cannot have both zero potential and zero field because the charges cannot be both same-sign and opposite-sign at once.
- At a zero-field point, a charge released exactly at that point has no resultant electric force and remains at rest.
This explanation was worth three marks in (9702/41/O/N/24 Q5(b)).
Potential is a signed scalar total. Field is a vector total and also the negative slope of potential. Treat the two zero conditions separately.
Your turnquick check
Can one point between two non-zero charges have both zero total potential and zero resultant electric field? Explain.
Show worked answer
No. Zero potential between the charges requires opposite signs, while zero resultant field there requires the field arrows to oppose and therefore requires the same sign.