# explain how the terms potential and potential difference are linked.

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#1
it is for my a level practical which is PAG 4.1 investigating resistor combinations and potential dividers.
help would be appreciated
thanks!
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1 year ago
#2
Potential difference is the work done in moving a unit positive charge from one point to another

Potential is the work done in moving unit positive charge from infinity to the point
Last edited by BobbJo; 1 year ago
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1 year ago
#3
So does the question just boil down to "explain why it's called potential difference"?

If so, I think it's because it's the potential difference in the energy that the charge carrier could gain or lose as it goes through a component. Potential difference supplied usually varies, I think the old spec included root-mean-square potential difference.
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#4
(Original post by Sinnoh)
So does the question just boil down to "explain why it's called potential difference"?

If so, I think it's because it's the potential difference in the energy that the charge carrier could gain or lose as it goes through a component. Potential difference supplied usually varies, I think the old spec included root-mean-square potential difference.
not really, it asks for the main similarity between potential and potential difference
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1 year ago
#5
(Original post by localmemelord)
not really, it asks for the main similarity between potential and potential difference
Both are measured in the same units (volts)

Both are quantities with units of energy per charge

Definition is similar (read post 2)
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#6
(Original post by BobbJo)
Potential difference is the work done in moving a unit positive charge from one point to another

Potential is the work done in moving unit positive charge from infinity to the point
(Original post by BobbJo)
Both are measured in the same units (volts)

Both are quantities with units of energy per charge

Definition is similar (read post 2)
0
1 year ago
#7
(Original post by localmemelord)
not really, it asks for the main similarity between potential and potential difference
Based on your opening post, I am thinking that you are attempting to make a link between the concept of potential and potential difference in a D.C. circuit. One thing you should be aware of is that both potential and potential difference are talking about the difference in potential between 2 points. You may be puzzled with what I am saying.

Let talk about potential difference first:
The potential difference between two points, A and B, equals the work done by the electric force when a UNIT positive charge moves from A to B. We can also define the potential difference between two points, A and B, as the energy transferred per unit charge as charge moves from A to B. Although the former definition is using work done by the electric force and the latter is using the term energy transferred, they are both essentially the same.
Something weird happens when we write potential difference between 2 points in a circuit. Say the current moves from A to B in a circuit, the potential difference between A and B is written as

VA - VB

NOT

VB - VA

(Something students may find it confusing!)

In A-level, I believe you would encounter the following definition about electric potential:

The electric potential at a point is defined as the work done (by an external agent) per unit positive charge in bringing charge from infinity to the point.

In the above definition, the point infinity is just a reference point and the potential at infinity is taken to be zero. So the potential at a point is essentially the potential difference between the point and the reference point (infinity). That is to say, we can define electric potential at a point to be:

The electric potential at a point is the electric potential difference between the point and the reference point (infinity) which is defined as the work done (by an external agent) per unit positive charge in bringing charge from infinity to the point.

You should not blindly apply this definition to the electric potential in a D.C. circuit. Since infinity is a reference point and the reference point that we tend to choose in a circuit is a point that is the earthed or the negative terminal of a battery where it is usually chosen to be zero potential. Thus, we can say that the potential at a point in the circuit is Vp is implying that potential difference between the point and the reference point in the circuit is Vp.
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