Does EMF Change During Battery Charging?

In summary, when you charge a battery, you apply a voltage greater than that of battery's in order to reverse the internal chemical reaction. The battery's emf is overcome by the voltage you apply to the leads, resulting in a potential gradient large enough to reverse the chemical flow. This is where the energy is stored.
  • #1
vikcool812
13
0
My doubt is that when we charge a battery we say that energy is transferred into it , but does the emf of a battery change in this process ? Is the emf same before and after charging , if yes then what actually happens during charging a battery ??

pls help !
 
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  • #2
When you charge a battery, you apply a voltage greater than that of battery's in order to reverse the internal chemical reaction. The battery's emf is overcome by the voltage you apply to the leads.

The net result is a potential gradient large enough to reverse the chemical flow by pumping energy into the reactions. This is where the energy is stored.
 
  • #3
so this means that the emf does not change , the extra potential applied just gets converted to chemical energy , did i get it right ??
 
  • #4
The emf is the electromotive force. This is what pushes the electrons through the circuit and back to ground. Charging a battery sort of provides a bigger emf in the other direction, driving the current backwards. So while the battery is charging the total emf is the other direction but the emf provided by the battery remains the same.
 
  • #5
A battery's emf does actually change as it is charged or discharged.
 
  • #6
now i am a bit confused , even i think that the emf changes , but i am unable to figure out the reason , could someone just explane it . pls...
 
  • #7
Hmm, it's been a while since I studied electrochemistry. I know it has to do with the change in Gibbs Free Energy (ΔG) for the chemical reaction involved, and ΔG depends on the concentration of ions in the battery solutions, which in turn depends on the charge state of the battery.

This site goes into it in detail, but assumes you are familiar with Gibbs Free Energy:
http://www.science.uwaterloo.ca/~cchieh/cact/c123/nernsteq.html

If nobody else can provide a better answer, I'll recommend you look at an introductory chemistry book (perhaps high school honors level, or college freshman level) that has a chapter devoted to electrochemistry. You'll need to be familiar with concepts like enthalpy and free energy, which would also be covered in such a book.

In particular, I can recommend the book Chemistry by Steven and Susan Zumdahl.
 
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1. What is EMF and how does it affect charging of a battery?

EMF, or electromagnetic force, refers to the potential difference between two points in an electric circuit. This difference in potential drives the flow of electric current, which is essential for charging a battery. A higher EMF can result in a faster charging rate for a battery.

2. Can EMF damage a battery during charging?

Yes, excessive EMF can cause damage to a battery during charging. This is especially true for lithium-ion batteries, which are commonly used in electronic devices. High EMF can lead to overheating and overcharging, which can reduce the battery's lifespan and even cause it to explode in extreme cases.

3. How does the type of charger affect the EMF during charging?

The type of charger used can greatly affect the EMF during charging. Some chargers, such as fast chargers, can produce a higher EMF which can lead to faster charging but also increase the risk of damage to the battery. Slower chargers typically have lower EMF and are safer for the battery in the long run.

4. Is it safe to use electronic devices while they are charging?

It is generally safe to use electronic devices while they are charging. However, it is important to use the proper charger and avoid using the device in extreme temperatures, as this can increase the risk of EMF-related damage to the battery. It is also recommended to avoid using cheap or third-party chargers, as they may not have proper safety protocols in place.

5. How can I reduce the EMF exposure while charging my devices?

To reduce EMF exposure while charging your devices, you can use a charger with lower EMF output, avoid using the device while it is charging, and keep the device away from your body during charging. It is also helpful to unplug the device once it is fully charged to avoid unnecessary exposure to EMF.

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