Can the electric potential be negative ?

[Ana Mido]

I have just solved a problem about electric potential and it is:
" A positive point charge of 1.0 nC is located at position x=0.00 . A second point charge q=-1.0 nC is located at x=0.10 m.
(a) What is the value of the electric potential on the x-axis at x=0.3 m ?
(b) What is the value of the electric potential on the at x=-0.050 m ? "

I have solved (a) and its answer is "-15". And I know that electric potential is a scalar quantity.

Explain that.

 

[hilbert2]

Electric potential can be negative if you go close enough to a negative charge. One important point, however: the potential does not have an absolutely defined value, you have to arbitrarily give it a value at a certain point. The usual choice in point charge problems is to decide that the potential is zero when you go infinitely far from all charges.

 

[pasmith]

I have just solved a problem about electric potential and it is:
" A positive point charge of 1.0 nC is located at position x=0.00 . A second point charge q=-1.0 nC is located at x=0.10 m.
(a) What is the value of the electric potential on the x-axis at x=0.3 m ?
(b) What is the value of the electric potential on the at x=-0.050 m ? "

I have solved (a) and its answer is "-15". And I know that electric potential is a scalar quantity.

Explain that.

Scalar quantities can be negative. What scalar quantities cannot do is depend on the direction of coordinate axes.

 

[Ana Mido]

Electric potential can be negative if you go close enough to a negative charge. One important point, however: the potential does not have an absolutely defined value, you have to arbitrarily give it a value at a certain point. The usual choice in point charge problems is to decide that the potential is zero when you go infinitely far from all charges.

Scalar quantities can be negative. What scalar quantities cannot do is depend on the direction of coordinate axes.

OK, is the answer true or is there any ambiguity in the problem ?

 

[rcgldr]

Electric potential is a signed value, with the convention of being postive for a field generated by a positive charge, and negative for a field generated by a negative charge. For a field generated by multiple charged objects, the sign of the potential would depend on location and the charge on the objects that generate the field.