Are the terminals of a well-charged battery neutral?

  • Thread starter Thread starter Ahsan Khan
  • Start date Start date
  • Tags Tags
    Battery Neutral
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
Sign up Log in
29 replies · 5K views
Ahsan Khan
Messages
270
Reaction score
5
Hi,It may looks illogical but concepts of electrostatics and current electricity force me to think so..'Are the terminals of a well-charged battery neutral?'my dc fan doesn't work when one of its wire is connected to the positive terminal of one battery and the other wire of the same fan to the negative of another battery.while its ok using only one battery.Is it possible for two bodies'of about same finite capacitance' being oppositely charged to have no potential difference?Please explain.Thanks a ton.
 
Physics news on Phys.org

Discussion

You have to have a complete circuit for electricity to flow. Can you do this with two separate batteries?
 
Thanks Turbo-1 for your attention to my question.But as far as i know whenever their is potential difference between two bodies,current flow from higher potential to lower potential till both the bodies attain same potential.in texts they show two they bodies of oppositely charged when connected by a single wire electrons flow flow from negatively charged body to positively charged body.
 
This can only happen when you have a complete circuit through which the current can flow. Draw it out.
 
It sounds that your answer for the question 'why current produce?' to be due to complete connection of wires rathar than due to difference of potential.
 
ovais said:
It sounds that your answer for the question 'why current produce?' to be due to complete connection of wires rathar than due to difference of potential.
You need both. Draw out a picture of your batteries with their poles, the wires and the load (fan in this instance).
 
Ok upon your advice i draw a diagram but still i am confused.See, does it just nead for the current to have its wires end to be connected to the source or is it also necessary for the terminals of the source to be connected through any conducting material besides the wire.If the latter'as per your view' why do a capacitor is able to draw current,when its two charged plates are not connected by a conductor.I think you need to re-look at the defination of close circuit.
 
Last edited:
I mean a close circuit should have been defined as the one in which the load must be connected i.e.the two wires join connecting the load from both sides, and the other ends of the wires must be connected to the terminals which have potential difference,irrespective wether the terminals are themselves are joint or separated from each other but they must have p.d.Please correct me if i am wrong.in ac also we can use phase wire of poles and can make the tab etc as neutal to run load
 
Last edited:
ovais said:
I mean a close circuit should have been defined as the one in which the load must be connected i.e.the two wires join connecting the load from both sides, and the other ends of the wires must be connected to the terminals which have potential difference,irrespective wether the terminals are themselves are joint or separated from each other but the must have p.d.Please correct me if i am wrong
Wrong. The two terminals cannot just have different potentials, but must be connected to one another to supply a path for current to flow.

You can prove this to yourself with a 2-cell flashlight. When the batteries are touching one another and you turn on the switch, the bulb lights up. If you take out the battery at the back of the flashlight and put a piece of tape over the small (+) terminal and reinsert it, you won't be able to turn the light on because you have interrupted the circuit. The bulb is still connected to the positive end of one battery and the negative end of the other battery, but no current can flow because you have interrupted the circuit.
 
So how is it possible for a capacitor and ac 'as i mentioned' to work,when their source terminals are not connected.And how does it possible for two oppositily charged spears to pass current when joint by a wire,while no cyclic connection is their.I think you need to look deeper.
 
Last edited:
ovais said:
So how is it possible for a capacitor and ac 'as i mentioned' to work,when they source terminals are not connected.And how does it possible for two oppositily charged spears to pass current when joint by a wire,while no cyclic connection is their.I think you need to look deeper.
I'm sorry. You'll have to educate yourself, since you seem intent on ignoring every bit of help that I have given you.
 
Well explain me how capacitor is able to draw current when its two wires are connected to a load.You must have been known that the plate of a capacitor are made of a conductor,and these plate have no conducting connection between them.The plates of a charged capacitor have equal and opposite charge but they are remain separated with a insulator weather the capacitor is working or not.so please explain me when oppositely charged separated plates can draw current why can't two oppositely charged termns can
 
You seem unable to grasp the concept of current-flow through a resistive load in a circuit. There is no point in discussing the behavior of capacitors until you have gotten past that simple concept.
 
O' Tor do not feel me bad.I just want to understand things.May their be some sort weakness in my mind due to which i am not getting you.I do not intend to tease any body.What that is going on either you are feeling difficulty understanding me or it may be some problem with me.Hope you are not dissappointed with me.
 
O' Tor do not feel me bad.I just want to understand things.May their be some sort weakness in my mind due to which i am not getting you.I do not intend to tease any body.What that is going on either you are feeling difficulty understanding me or it may be some problem with me.Hope you are not dissappointed with me.Do anybody know my answer?Please help.Thanks
 
Consider two identical spears of iron ,if some how one spear is given neagtive charge and the other is given a positive charge.And thesd two spears are then place 10meter apart with both separatly on an insulated stand.Now the the spears are connected to nothing other than air or say they are in vacuum.Now could you tell me what happen when this system of two spears is joint by a wire.The spears are themselves in no connect other than external wire or external circuit.Thanks.
 
ovais said:
Consider two identical spears of iron ,if some how one spear is given neagtive charge and the other is given a positive charge.And thesd two spears are then place 10meter apart with both separatly on an insulated stand.Now the the spears are connected to nothing other than air or say they are in vacuum.Now could you tell me what happen when this system of two spears is joint by a wire.The spears are themselves in no connect other than external wire or external circuit.Thanks.

If you have two separated bodies of opposite charge, the charges will try to neutralize : if you touch the first of your "iron spears" (say negative one) with an iron wire, the excessive charge on the spear will distribute across both spear andwire, but you will notice nothing of that. If you now touch the positive "spear" with you wire, you'll most probably observe a spark (=short manifestation of charge neutralization, or so to say, "current"): you could call this electrostatic discharge (ESD), if you like.

If there is no machinery which supplies new charge to the "iron spears", this spark will be the only thing which happens
 
ovais said:
Hi,It may looks illogical but concepts of electrostatics and current electricity force me to think so..'Are the terminals of a well-charged battery neutral?'my dc fan doesn't work when one of its wire is connected to the positive terminal of one battery and the other wire of the same fan to the negative of another battery.while its ok using only one battery.Is it possible for two bodies'of about same finite capacitance' being oppositely charged to have no potential difference?Please explain.Thanks a ton.

It is possible to have current flow when arranged as you've stated, but it requires far greater voltage potentials and the flow is typically brief, lasting only as long as is required for both points to reach the same level of charge, at which point no additional current will flow. 12 volts is just too low to accomplish the task.
 
This is a good question, ovais. Indeed, current will flow between two objects if one is negatively charged, one is positively charged, and they are connected by a wire. And current will flow if you connect the positive terminal of one battery to the negative terminal of another, but only briefly.

See, a battery operates by containing chemicals that tend to react. When the reaction occurs, ions (i.e., atoms bearing charge) are pushed from one electrode to another within the battery. At the negative electrode, each ion changes to an uncharged atom and an electron or electrons. At the positive electrode, an electron or electrons combines with an uncharged atom to produce an ion. The ions move through a paste called an electrolyte (by definition, a substance that allows ionic charge transfer).

When the battery is assembled, the same reaction occurs briefly, until electrons build up on the negative electrode and are depleted at the positive electrode. This quickly stops the reaction. The battery is now ready for use.

When you connect the positive terminal of one battery to the negative terminal of another, the reaction will continue briefly and charge will flow briefly, but you haven't fulfilled the requirements for continuous power because the negative terminal of the first battery still has a surplus of electrons and the positive terminal of the second is still depleted of electrons.

It's only when you connect a load to a battery or batteries in a circuit loop that you can transfer electrons from the negative electrode to the positive electrode via electronic current flow. This allows the reaction to continue. Does this make sense?
 
hello mapes, first of all thank you your answer makes full sense you seem to understand my query.you have answered from inside the battery that's what i want.now i very much understand why charge don't continously flow from one battery to another as you said.But I will be very thankfull to if you explain this more openly and in more informative way,since i at this stage is satisfied with it but still can not explain it to others on my own.REGARDS
 
Last edited:
Sure, which part would you like clarification on?

The water analogy is often useful when discussing current flow. A battery is analogous to a pump that provides a constant pressure (where we're comparing the output point or negative terminal to the input point or positive terminal). The pump requires an upstream water source and a downstream water sink; if either of these are blocked, the pump stops moving fluid.

Connecting the negative terminal of one battery to the positive terminal of another battery is analogous to connecting two pumps but leaving the output of one and the input of the other blocked. It's not possible to get sustained fluid (or electron) flow this way.
 
yes i want to clarify the following point from your first reply-
After a momentry current flows from positive terminal of one battery#1 to negative terminal of another battery#2 ,the electrolyte of battery#1 should have net negative charge while the electrolyte of battery#2 should have a net positive charge due to small flow of electrons from battery#2 to battery#1 during momentry current.this make me think that the ONLY REASON why a continuous flow of current DONOT take place(when +ve of battery#1 is connected to -ve of battery#2) is because negatively charged electrolyte of battery#1 do not allow further entry of electrons from battery#2 and in the sameway positivly charged electrolyte of battery#2 do not allow exit of electrons.Is this what Mapes, you want to say from your first reply to my question.the statement current needs complete circuit is true but not informative. thanks
 
Ha.. ha.''Sounds good'',sounds good to me, but am i clear?Is my interpretation true?
 
Last edited:
Sure. I would say that the charge builds up on the electrodes, though, rather than in the electrolyte.
 
It was just all alright before the statement 'charge i.e. opposite charge builds up on the electrodes' is it possible for a single metal bar 'electrode here' to behave partially positive and partially negative?I mean what charge will be on the positive terminal of battery#1 and that on the negative terminal of battery#2 after they connected to each other.Will all the excess electrons of negative terminal of battery#2 will go to posiive terminal of battery#1.what charge will now each of the two terminal have
 
No, the electrically connected terminals will have the same potential. The negative terminal of battery #1 will have a negative potential relative to this, and the positive terminal of battery #2 will have a positive potential relative to this. The electric fields from these potentials will halt the electrochemical reactions that would normally provide energy in a connected circuit.
 
O.k. i understand that how the electrostatic potential of negative terminal of battery #1 and the positive electrode of battery #2 ristricts the electrochemical reaction which provides energy and that the electricaly
connected terminals have same potential.what about the charge on the connected terminals.do they become neutral? if yes how do they meet neutrality if the batteries are of different size or of different potential or voltage.REGARDS
 
Last edited:
I'm not sure. I don't think we can assume the connected terminals are neutral; my hunch is that they could end up negatively or positively charged depending on the details of the reaction, the material, and the electrolyte. I'll think about it, though.

Is this based on curiosity or are you building something interesting?
 
Just curiosity, building nothing.thanks, 99 percent of the curiosity is solved. I am highly satisfied.
 

Similar threads

Are the terminals of a Battery neutral?
  • Alex Hughes
  • · Replies 27 ·
  • Electrical Engineering
Replies
27
High School Energy Conservation w/ Charged Battery Time Travel
  • Lars Krogh-Stea
  • · Replies 3 ·
  • Special and General Relativity
Replies
3