Electron flow and electric field question

Question

My understanding is that the electric field lines of a proton goes outwards and an electron goes inwards, are theses properties the same for electron flow or is just for conventional current?

I think it makes more sense if the electric field lines of an electron is outwards instead of inwards, why? Protons have more mass, and should be producing an inwards electric field lines. Also, If the above is true, the electrons would flow with the electric field instead of against it in a closed circuit. Also, does that mean the magnetic field lines are reversed and the south pole magnetic field lines are going outwards?

I'm new to physics and I need help understanding the basics.

Answer 1

• Protons have more mass, and should be producing an inwards electric field lines

• No electric field lines do not depend on mass

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• Electrons would flow with the electric field instead of against it in a closed circuit
• Three statements here
• 1.The force of interaction between the charges is attractive if the charges have opposite signs (i.e., F is negative) and repulsive if like-signed (i.e., F is positive).
• 2.To provide a definition of current independent of the type of charge carriers, conventional current is defined as moving in the same direction as the positive charge flow.
• 3.Electric field lines are in the outward direction from a proton hence a proton will repel a proton, and thus move outwards. Electric field lines are inwards for an electron, hence an electron would attract a proton.

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Combining the three- in metals where the charge carriers (electrons) are negative, conventional current is in the opposite direction as the electrons. In conductors where the charge carriers are positive, conventional current is in the same direction as the charge carriers.

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• magnetic field lines are reversed and the south pole magnetic field lines are going outwards

• By convention, the field direction is taken to be outward from the North pole and in to the South pole of the magnet.

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• electric fields are lines of force that have direction and magnitude

• -Yes

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Helpful links

1. What causes like electric charges to repel and opposite electric charges to attract at the smallest level?
2. How do electrons repel?
3. Electric lines of force

Answer 2

Protons have more mass, and should be producing an inwards electric field lines.

First, the mass of the proton isn't important. The electric field is produced by the charge of the particle, not its mass. Protons and electrons have equal (but opposite) charge, despite their vast difference in mass.

Second, the direction of the electric field tells you which direction would the force on a positive charge be if you put it in the field. Since two protons repel each other, you know that the electric field from a proton must point away from it.

Also, If the above is true, the electrons would flow with the electric field instead of against it in a closed circuit.

An electron (which has negative charge) is attracted to a proton. That is, it experiences a force toward the proton. And the force on a negative charge in an electric field is in the opposite direction from the field vector. So again, this is consistent with the electric field produced by the proton pointing away from the proton, not inwards towards it.

None of this has any bearing on the difference between conventional current and electron current. Whether you work with conventional or electron current, you'll still consider the electric field pointing away from positive charges and towards negative charges. You'll just have a different convention for the direction you assign to the current relative to the movement of the carriers.

Answer 3

In addition to other answers, it might be pointed out that classical electrodynamics enjoys a charge conjugation symmetry. Thus, if one chooses the opposite convention in which the electron is assigned a positive charge (and so the electric field lines flow outward from the electron) and a proton is assigned a negative charge (and so the electric field lines flow into the proton) then all the physical results would turn out exactly the same. For example, an electron would still repel an electron and attract a proton with the same force as before, and vice versa.

What one should not do is to imagine field lines going outward from a negative charge. Because the divergence of the electric field is supposed to give the electric charge density according to Gauss's law. Thus, classical electrodynamics doesn't permit imagining outward flowing electric field lines from a negative charge. If one insists then one can imagine putting a negative sign in the Gauss's law and consistently re-interpreting all the results and still arriving at the same physical predictions--however, this is futile as it simply amounts to renaming the charges which we have already acknowledged as the charge conjugation symmetry.

Answer 4

Electric charge and the assosiated field strength due to their charge has nothing to do with their mass. The charge on the proton and the electron are the exact same and thus electrically, they don't matter at all.

Secondly, the proton and electron do gravitationally interact, but that is so irrelevant since it produces an acceleration that is way smaller that an electron would barely move (despite its low mass compared to the proton).

$$F=ma$$ $$a=F/m$$ $$F=Gm_1m_2/r^2$$ $$a=Gm_1/r^2$$ Here, $G$ is like $10^{-11}$ and $m_1$ is like $~10^{-27}$ (for electron) which contributes to an acceleration that is negligible to observe (electron acceleration here). Replace the mass value for the proton, and we get similar accelerations.

The field lines point towards the electron because it is how scientists defined them. If you place a positive charge over a field line, the direction the charge moves is the direction of the field lines. We could have chosen the conventional charge to be negative. But scientists chose that convention of positive charges.