Comparing Electrostatic Potentials of Positive and Negative Charges

In summary: However, the electrostatic potential of the charge Q itself is the same in both cases, as it depends only on the magnitude of the charge and the distance between the charges. This is because the electrostatic potential is a measure of the potential energy per unit charge, so it is independent of the sign of the charge. In summary, the electrostatic potential of the charge Q remains the same regardless of the sign of the test charges brought near it, but the electrostatic potential energy of the test charges themselves will be different depending on their sign.
  • #1
Tony11235
255
0
This is more of a general question and not a homework question, just to make it clear. Say two test charges are brought separately, one after the other, into the vicinity of a charge +Q. First test charge +q is brought to point B a distance r from +Q. This charge is removed and a test charge -q is brought to the same point. Now do we say that the electrostatic potential of +q is greater because it has a positive sign compared to -q? Or do we say their potentials are the equal because their magnetudes are the same? I assume it's the latter, isn't it?
 
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  • #2
The electrostatic potential of the system is always
[tex]
\phi(\vec{r}) = \frac{1}{4 \pi \epsilon_0} \frac{Q}{r}
[/tex]
assuming the test charges are truly infinitesimal (i.e. we neglect their contribution).

The electrostatic potential energy (or just energy) is
[tex]
E_{q}= \frac{1}{4 \pi \epsilon_0} \frac{qQ}{r}
[/tex]
in the case of a positive test charge and
[tex]
E_{-q}= -\frac{1}{4 \pi \epsilon_0} \frac{qQ}{r}
[/tex]
in the case of a negative test charge. The energy or electrostatic potential energy is different in each case, but the electrostatic potential of the charge Q is the same in both cases. It's mostly a matter of terminology.
 
  • #3
Physics Monkey said:
The electrostatic potential of the system is always
[tex]
\phi(\vec{r}) = \frac{1}{4 \pi \epsilon_0} \frac{Q}{r}
[/tex]
assuming the test charges are truly infinitesimal (i.e. we neglect their contribution).

The electrostatic potential energy (or just energy) is
[tex]
E_{q}= \frac{1}{4 \pi \epsilon_0} \frac{qQ}{r}
[/tex]
in the case of a positive test charge and
[tex]
E_{-q}= -\frac{1}{4 \pi \epsilon_0} \frac{qQ}{r}
[/tex]
in the case of a negative test charge. The energy or electrostatic potential energy is different in each case, but the electrostatic potential of the charge Q is the same in both cases. It's mostly a matter of terminology.

So to clear this up, the electrostatic potential energy of the positive test charge is greater?
 
  • #4
Yes. It has positive energy while the negative charge has negative energy.
 

What is electrostatic potential?

Electrostatic potential is the amount of electrostatic potential energy per unit charge at a given point in space. It is a scalar quantity that represents the potential energy of a charged particle in an electric field.

How is electrostatic potential different from electric potential?

Electrostatic potential refers to the potential energy of a charged particle in an electric field, while electric potential is the potential energy of an electric charge at a specific location in an electric field. Electrostatic potential is dependent on the properties of the electric charge, while electric potential is dependent on the position of the charge.

What is the unit of electrostatic potential?

The unit of electrostatic potential is volts (V) in the SI system. It can also be expressed in other units such as joules per coulomb (J/C) or newtons per coulomb (N/C).

How is electrostatic potential calculated?

Electrostatic potential is calculated using the formula V = kQ/r, where V is the electrostatic potential, k is the Coulomb's constant, Q is the magnitude of the charge, and r is the distance from the charge to the point where the potential is being measured.

What is the significance of electrostatic potential in physics?

Electrostatic potential plays a crucial role in understanding the behavior of charged particles in an electric field. It is used in various applications such as in the design of electrical circuits, particle accelerators, and in studying the properties of materials in electrostatics experiments.

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