# Flow of electrons [duplicate]

Why do electrons flow from lower potential to higher potential? According to the first law of thermodynamics, energy flows from higher to lower potential spontaneously. Electrons do contain energy but why do they flow from lower to higher potential?

• Can you please give an example? Flow of energy and movement of charge across a potential are not exactly the way you describe. – joseph h Nov 18 '20 at 5:57
• This question has already been asked. Check the answer at physics.stackexchange.com/questions/91574/… – GiorgioP Nov 18 '20 at 6:27
• @GiorgioP If you think it is already answered then please use the "close as a duplicate" process. – StephenG Nov 18 '20 at 6:50
• @StephenG I use to wait before starting a closing procedure. Just to give time to the OP to modify or clarify his/her question. I do not think it is a race. – GiorgioP Nov 18 '20 at 6:56
• @BillN I agree that previous answers to the same question are not completely satisfactory (although I linked the page containing the best answer IMO). However, this is not a good reason for asking again the same question, according to this site policy. Having enough reputation, it is possible to set a bounty to encourage better answers. – GiorgioP Nov 18 '20 at 15:31

## 5 Answers

Why do electrons flow from lower potential to higher potential?

The short answer is it’s because high and low potential are defined by convention with respect to the flow of positive charge and not electrons. By convention the direction of the electric field is the direction of a force that a positive charge would experience if placed in the field. Consequently, moving a positive charge in a direction opposite to the direction of the electric field (e.g., moving a positive charge towards another positive charge) increases the potential and potential energy of the positive charge. Such movement is not spontaneous since an external force must be applied to move the positive charge against the repulsive force of the electric field.

Electrons do contain energy but why do they flow from lower to higher potential?

Although moving an electron in the opposite direction of an electric field is moving the electron from low to high potential, because of how low and high potential are defined, the electron loses potential energy. The movement of the electron is spontaneous due to attraction force of the electric field. The gravitational analogy is the loss of gravitational potential energy of a falling object, where the gravitational field is analogous to the electric field and the object is analogous to the charge.

Hope this helps.

The phenomenon can be explained by:

Intuition

Consider the following situation:

Electrons flow from A to B since repulsion between electrons would be more in A than in B.

The formula for electric potential is : $$V(r)=k\sum{\frac {Q_i }{r_i}}$$.

So , $$V_A$$ is negative and $$V_B$$ is positive. Hence B is at higher potential.

We already know electrons flow from A to B. Hence electrons flow from low potential to high potential.

Energy Consideration

At a point of comparatively high potential, a positive charge would have high potential energy compared to that at a point of low potential. For a negative charge/electron , it would have high potential energy at a point of low potential than at a point of high potential. This can be verified from the formula:

$$U(r)=kq\sum{\frac {Q_i }{r_i}}$$

or

$$U(r)=qV(r)$$

Hence electrons flow from low to high potential.

Yes ideally Higher potential and lower potential are for positive charges so a positive charge will go from higher potential to lower potential.

But an electron see higher potential as potential with negative sign and greater magnitude and similarly for lower potential.

So a higher potential for an electron is lower potential for it.

For positive charge $$V_{A}>V_{B}$$

For negative charge $$-V_{A}<-V_{B}$$

In a nutshell So higher potential for proton is lower potential for electron

• Unless you distinguish more clearly between electric potential and potential energy your answer is confusing. However, take into account that this question is a duplicate. – GiorgioP Nov 18 '20 at 6:27

You should distinguish potential, say V, from potential energy, $$E_V = qV$$. A object will always move to a position of lowest potential energy, so a negative charge will move to the position of highest potential.

The issue is not whether the potential increases or decreases as the electron moves. The important construct is what happens to the potential energy of the system as the electron moves.

In general, a system under the influence of internal forces will reorient to minimize the potential energy of the system subject to constraints of outside and non-conservative forces. A mass in a gravitational field will move to a location in the field so that the potential energy is the smallest it can be before it is stopped by a floor or table or hand, etc. A mass hanging on a spring in a gravitational field will have an equilibrium position in which the sum of the potential energies due to gravity and the spring are at a minimum. Displace the mass from that position and the mass will reorient (move) toward that minimum.

The same is true for electrical systems. In your case, the electron will move toward a new position to reduce the potential energy of the system. That means, by definition of what's positive and negative (Thank you Ben Franklin) means that an electron moves to higher potential (because of the definition of potential being the potential energy per unit (positive) charge).

Also, think about the direction of the force on a charge: $$\vec{F}=q\vec{E}$$. That means that the force on an electron is opposite the direction of the $$\vec{E}$$ field. The $$\vec{E}$$ field points toward lower potential (not potential energy!) because of the definitions of work, potential energy, and potential. So the electrical force on an electron accelerates it toward a higher potential region of space.