Potential Difference between the Two Points

Finding the Potential Difference between the Two Points in Circuits with Examples

Finding the Potential Difference between the Two Points in Circuits
Potential difference between two points in circuit is the energy lost by the charge in being transferred from one point to another. For example, potential difference between A and B is found with following formula;
VAB=VB-VA=∑ε-∑i.R
This formula shows the energy lost by charge moving from point A to point B.
We should first find the direction of the current to determine values ∑ε and ∑i.RIf you take the sign of batteries having same direction with current as “+” then you must take oppositely connected batteries as “-“.

potential difference between two points


If the direction of the current and current passing through the resistor are the same then we take i.R as "+", if they are in opposite directions then we take i.R as "-".
In the circuit given below, if the direction of the current is shown like below, then potential difference between the points A-B and C-B are;

potential difference between two points example






VAB=VB-VA= -ε2-(+i.R1+i.R2)
VCB=VB-VC= -ε3-(-i.R3)


Example: Find the potential difference between the points A and B in the given circuit below.
Current of the circuit is in the direction of battery current.
potential difference  example







potential difference example







Example: Find the power of the resistor R1.

potential difference example









εeq21=34V-10V=24V
Equivalent resistance of the circuit is;

potential difference example

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