Potential of terminals of battery

  • Thread starter Thread starter gracy
  • Start date Start date
  • Tags Tags
    Battery Potential
AI Thread Summary
The discussion centers on the potential of battery terminals, specifically a 9V battery, and the concept of potential difference. It emphasizes that while various potential values can be assigned to the positive and negative terminals, the actual potential is relative to a reference point, which is often unspecified. The potential difference of 9V remains constant regardless of how the terminals are grounded or referenced. The conversation highlights that understanding the relative potential is crucial in certain contexts, although it may not always be necessary for practical applications. Ultimately, the focus is on the significance of potential differences over absolute terminal potentials.
gracy
Messages
2,486
Reaction score
83
No it is not a homework problem I made it myself in order to clearly explain what I am trying to ask.The question could be invalid and silly therefore .If there is a 9V battery What is the potential of it's positive and negative terminals respectively?

If positive terminal's potential is 3V and potential of negative terminal -6V then there would be potential difference of 9V. Similarly if positive terminal's potential is 2V and potential of negative terminal -7v then there would be potential difference of 9V. So many answers are possible therefore potential of one terminal should be given.
Am I making sense?Or all of these are wrong?
 
Physics news on Phys.org
Only potential differences are physically meaningful. Given a battery with a potential difference of 9 V between the two terminals, there is not enough information to tell you the potential of either positive or negative terminal relative to some unspecified reference.

For instance, you could ground the positive terminal. The negative terminal would then be at -9 V relative to the ground. Or you could ground the negative terminal. The positive terminal would then be at +9 V relative to the ground. Or, as you suggest, you could arrange for the two terminals to be at +3 V and -6 V. That would be perfectly reasonable.
 
  • Like
Likes gracy
gracy said:
If positive terminal's potential is 3V and potential of negative terminal -6V then there would be potential difference of 9V. Similarly if positive terminal's potential is 2V and potential of negative terminal -7v then there would be potential difference of 9V. So many answers are possible therefore potential of one terminal should be given.
Am I making sense?Or all of these are wrong?

You are basically correct.

However ask yourself 3V relative to what ?... and do you really need to know the voltage relative to that? My phone works just fine even when my hand is charged to several thousand volts by static electricity. Sometimes it does matter. Can you think of a situation?
 

Thread '1:1 versus 2:1 Mechanical Advantage debate'

The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
View full post »

Thread 'Newton's first law?'

Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
View full post »
Thread 'Beam on an inclined plane'

Thread 'Beam on an inclined plane'

Hello! I have a question regarding a beam on an inclined plane. I was considering a beam resting on two supports attached to an inclined plane. I was almost sure that the lower support must be more loaded. My imagination about this problem is shown in the picture below. Here is how I wrote the condition of equilibrium forces: $$ \begin{cases} F_{g\parallel}=F_{t1}+F_{t2}, \\ F_{g\perp}=F_{r1}+F_{r2} \end{cases}. $$ On the other hand...
View full post »

Similar threads

I Potential difference between a battery's terminal and Earth ground
2
Replies
58
Views
4K
Change in potential of terminals of batteries
Replies
7
Views
2K
Do Electrons Travel from the Positive to the Negative Terminal in a Battery?
Replies
11
Views
3K
Mechanisms Involved When Charging a Battery
Replies
10
Views
1K
Potential difference: positive or negative?
Replies
15
Views
4K
At the atomic level, why is voltage added when batteries are connected in series?
Replies
2
Views
2K
Potential Difference between earth and battery
Replies
12
Views
4K
How does a simple circuit work?
Replies
12
Views
1K
I An attempt to understand the associated variable conventions in circuits
Replies
1
Views
2K
Why does the potential of A decrease when plate B is nearby?
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top