Why Does the Internal Resistance Graph Have a Negative Gradient?

In summary, when taking internal resistance into account, the voltage/current graph will have a negative gradient due to the inclusion of the internal resistance (r). This is in contrast to the positive gradient seen in ohmic resistors. This is because the equation for potential difference (V) in a circuit with internal resistance includes a negative co-efficient (-r) for current (I). The y-intercept (E) remains the same.
  • #1
Vaseline
4
0
When taking internal resistance into account, voltage/current graph has negative gradient (i.e. internal resistance).?

My thoughts...

Because for ohmic resistors, graph has a positive gradient. Why does one say that when V=0, Current = max, whilst the other says that when V=0, Current = 0?
 
Physics news on Phys.org
  • #3
Vaseline said:
When taking internal resistance into account, voltage/current graph has negative gradient (i.e. internal resistance).?

My thoughts...

Because for ohmic resistors, graph has a positive gradient. Why does one say that when V=0, Current = max, whilst the other says that when V=0, Current = 0?

My question was answered in that thread, this is the result I got.

[itex] E = I(R+r) [/itex] where R is the total resistance in the circuit and r is the internal resistance of the cell or battery. From this we can see that,

[itex] E = V + Ir [/itex]

and,

[itex] V = E - Ir[/itex]

When plotting a graph of potential different against current it is clear that the current I has a negative co-efficient: -r. Hence -r is the gradient of the line, and E is the y intercept. y=mx +c (remember?) this is just V=-rI+E.
 

FAQ: Why Does the Internal Resistance Graph Have a Negative Gradient?

What is an internal resistance graph?

An internal resistance graph is a visual representation of the relationship between the voltage and current in an electrical circuit. It shows how the current changes as the voltage is varied, and can help determine the internal resistance of the circuit.

Why is an internal resistance graph important?

An internal resistance graph is important because it can help in the analysis and troubleshooting of an electrical circuit. It can also provide insight into the performance and efficiency of a circuit, and can be used to make improvements or optimizations.

How do you interpret an internal resistance graph?

To interpret an internal resistance graph, you need to look at the shape and slope of the line. A steep slope indicates a low internal resistance, while a flat slope indicates a high internal resistance. The intercept of the line with the y-axis represents the open circuit voltage, and the intercept with the x-axis represents the short circuit current.

What factors can affect the shape of an internal resistance graph?

The shape of an internal resistance graph can be affected by several factors, such as the type of circuit components, the material used for the conductor, the temperature of the circuit, and the length and thickness of the conductor. These factors can alter the internal resistance of the circuit and thus impact the shape of the graph.

How can an internal resistance graph be used in real-world applications?

An internal resistance graph can be used in various real-world applications, such as in the design of electrical circuits for different devices and systems. It can also be used in the analysis and troubleshooting of faulty circuits, as well as in the optimization of circuit performance. Additionally, internal resistance graphs can be used in the testing and evaluation of new materials and components for use in electrical circuits.

Similar threads

Internal Resistance Affect the Balancing Length in a Potentiometer?
Replies
12
Views
437
Ohm's Law graphing inversed gradient value
Replies
3
Views
1K
Reading of Ammeter for this circuit with Voltage Controlled Resistors
Replies
9
Views
428
Current in a circuit without external resistance
Replies
8
Views
1K
Finding the internal resistance of battery
Replies
10
Views
3K
Gradients of Graphs with and without Rates of Change
Replies
19
Views
2K
Calculating E.M.F and Internal Resistance of a Cell in Series Circuit
Replies
2
Views
2K
Mechanisms Involved When Charging a Battery
Replies
10
Views
692
Unraveling the Mystery of EMF Internal Resistance
Replies
2
Views
2K
Linking gradient of IV graph and resistance
Replies
5
Views
2K

Hot Threads

Recent Insights

Back
Top