Flow of Electrons in Batteries: Current? Time?

In summary, a battery participates in a closed circuit. When the electrons have transferred to the positive terminal, current flows. The time for this to happen depends upon the current draw by the external circuit and the available quantity of chemicals internally.
  • #1
shanewatson
8
0
in a battery, when all the electrons have transferred to the positive terminal ( i mean both terminals have same no. of electrons) , then do any current flow? if no , then how much time does it take for all electrons to be transferred fron negative to positive terminal? (i know it is a silly question but i need an easy logical answer)
 
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  • #2
Both terminals always have the same number of electrons.

A battery participates in a closed circuit.

In the ouside part of the electrical circuit we can say electrons move from the negative terminal towards the positive.

Within the battery they move the other way, completing the circuit and so maintaining the number around the circuit.

The electron 'movement' is powered by the chemical reaction within the battery.
This reaction cannot take place unless the circuit is completed externally so current only flows in a complete circuit.
When the chemicals are all used up the reaction ceases and so does the current.
The time for this to happen depends upon the current draw by the external circuit and the available quantity of chemicals internally (ie battery size or capacity).

Does this help?
 
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  • #3
first of all, the positive and negative terminals obviously DO have different numbers of charged particles...be they ions or electrons...otherwise there would be no potential difference between them...just as there are more negative charges on one plate of a capacitor than the other ...

see here for basic battery operation:
http://en.wikipedia.org/wiki/Battery_(electricity)#Principle_of_operation

In the redox reaction that powers the battery, cations are reduced (electrons are added) at the cathode, while anions are oxidized (electrons are removed) at the anode
You can get some standard figures to compare batteries regarding how long they will deliver current from the ampere hour rating and Peukert's Law:

http://en.wikipedia.org/wiki/Automotive_battery#Terms_and_ratings
http://en.wikipedia.org/wiki/Peukert's_LawAlthough I don't think automotive batteries typically have an ampere hour rating provided
[ they seem to use cold cranking amps [CCA]as a standard measure] all deep cycle batteries that I have seen do. These ratings are usually based on a 20 amp discharge rate in the US...so an 8D deep cycle lead acid battery, for example, might have a rating of about 220 amp hours...at 20 amps, it will provide current for 220/20 or about 11 hours...after which the voltage is down to 10.5 volts...many loads will not work at or beyond that but additional current will flow at a reduced rate.

Peukerts law is the more accurate way to calculate how long a current will continue to flow.
 
  • #4
the positive and negative terminals obviously DO have different numbers of charged particles

If this is true then the salt bridge in your Wiki article should not necessary. Simply connecting the terminals by a wire should enable all these excess electrons to flow between the half cells without the bridge.

Of course this cannot and does not happen so perhaps you would like to explain further?
 
  • #5


Yes, current will continue to flow in a battery even when the number of electrons is equal in both terminals. This is because the flow of electrons is not the only factor that determines current. The other important factor is the potential difference, or voltage, between the terminals. As long as there is a difference in voltage between the positive and negative terminals, current will flow.

The time it takes for all electrons to be transferred from the negative to the positive terminal will depend on the specific battery and its capacity. This is because different batteries have different chemical compositions and sizes, which affect the rate at which electrons can flow. Additionally, the amount of current being drawn from the battery will also impact the transfer of electrons. Generally, the higher the current, the faster the transfer of electrons. However, it is important to note that batteries have a limited capacity and will eventually run out of electrons, resulting in a decrease in current flow.
 

1. How do electrons flow in a battery?

Electrons flow in a battery through a circuit. When the circuit is closed, the electrons flow from the negative terminal of the battery, through the circuit, and back to the positive terminal of the battery.

2. What is the role of electrons in a battery?

Electrons are responsible for creating an electric current in a battery. As they flow through the circuit, they create the energy that powers the device connected to the battery.

3. How does the flow of electrons affect the current in a battery?

The flow of electrons directly affects the current in a battery. The more electrons that flow through the circuit, the higher the current will be.

4. Does the flow of electrons in a battery change over time?

Yes, the flow of electrons in a battery can change over time. As the battery discharges, the number of available electrons decreases, which can result in a decrease in the current.

5. How does the flow of electrons in a battery relate to the battery's lifespan?

The flow of electrons in a battery is a key factor in determining its lifespan. As the battery is used and electrons flow through it, the battery's chemicals undergo changes that can eventually lead to a decrease in its ability to hold a charge. This can result in the battery needing to be replaced.

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