Problems understanding voltage

[pconstantino]

Why do they say an electron gains energy inside a battery ?

the charge of an electron doesn't change after passing through a battery,

why does the potential energy increase?

what does it mean to lose energy after passing thru a resistor?

what energy is there to lose? kinetic?

thank you

 

[Drakkith]

The electrons on the negative part of a battery have the potential ability to be transferred to the positive side and in the process can be used for work. That is what they mean by potential energy increasing for an electron inside the battery.

Once depleted, the electrons in the battery no longer have that potential, since the chemical reaction which allows them to be transferred can no longer take place.

Placing a resistor in a circuit will cause fewer electrons to move through the circuit thanks to the resistance. The side of the circuit before the resistor still has the potential to give full current and voltage, but after the resistor it has less of each. The energy "lost" is electric potential energy, not kinetic.

 

[ZealScience]

Because they are driven by e.m.f from anode to cathode. In the process electron experience repulsion from the cathode and attraction from anode. Thus positive work is done, which means energy is gained.

If you learn more about E&M youwould clearly know that potential energy doesn't simply depend on charge but also the position in the E field. If you learn about Kichoff's rule you would know than resistance would have an E field inside, which decreases potential (they are not super conductors). And I don't think that electron doesn't lose much kinetic energy (apart from the little bit decrease in mass), they are moving at the same velocity.

 

[pconstantino]

sorry i still don't "get it".

ive studied electric and magnetic fields, i understand what potential energy is and i accept it for a particle in an electric field but i can't understand it when it;s in a wire.

what makes the electrons inside a resistor to lose E P.E. ? even if they bump into atoms, they would still be at about the same position and E P.E is a function of position as well as charge.

 

[ZealScience]

sorry i still don't "get it".

ive studied electric and magnetic fields, i understand what potential energy is and i accept it for a particle in an electric field but i can't understand it when it;s in a wire.

what makes the electrons inside a resistor to lose E P.E. ? even if they bump into atoms, they would still be at about the same position and E P.E is a function of position as well as charge.

No, electrons are continuously flowing which is a current (though they are not moving throughout the circuit). In resistors, there is an electric field, because they are not superconductive. So electrons are changing position in electric field.

 

[Discord7]

what does it mean to lose energy after passing thru a resistor?

what energy is there to lose? kinetic?

thank you

Back in my day, just working with electronic circuitry, we went years without talking about electric fields, so I probably don't grasp what you are looking for. The law of conservation of matter and energy served well in troubleshooting. A current through resistance produces heat, and production of heat surely accounts for the removal of energy from the potential source in a circuit. It seems as though electrons with their push and pull upon other charged particles become mistaken as energy, but they are more of a medium for storage and collection of energy. Crowd them closer to each other to store energy. Their relative positions about an atom are not of much interest unless you are wearing a smock.

We call electrons charged particles, but you cannot discharge them. "Charged" sounds like somewhere along the line someone applied that charge but that has never happened. "Charge" is often what you call it when you energize something. An excess of electrons on an isolated sphere is called a charge, but if you want to electrically energize such a body you have to crowd them away from where they prefer to be, and that action could also be called giving it (the sphere) a charge.

 

[Drakkith]

sorry i still don't "get it".

ive studied electric and magnetic fields, i understand what potential energy is and i accept it for a particle in an electric field but i can't understand it when it;s in a wire.

what makes the electrons inside a resistor to lose E P.E. ? even if they bump into atoms, they would still be at about the same position and E P.E is a function of position as well as charge.

A particle in a conductor does not behave like a particle simply in an electric field. The resistance of the material greatly effects their behavior. Particles have less potential energy when the resistance of the material is higher because it takes more energy that it otherwise would to get them to move.

In a conductor the electrons are not bound to individual atoms, so it takes very little force to cause them to move. I don't think it is that electrons "bump" into atoms in a resistor, but that the atoms themselves don't want to give up their valence electrons. Maybe the liberating of and then binding of the electrons is the source of the heat? (Would love an answer to this from someone, I really don't know)