What Is the Interpretation of an Integral Equation with a Proportional Variable?

Click For Summary

Homework Help Overview

The discussion revolves around the interpretation of an integral equation involving a variable that is proportional to the integrand, specifically in the context of electric potential and electric fields. The equation in question is $$\Delta V = - \int_a^b \vec E \cdot d \vec s$$, which relates the change in electric potential to the work done by the electric field.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants explore the relationship between the change in potential and the integral of the electric field, discussing the transition from discrete sums to integrals. Questions arise regarding the specific variable that is proportional to the integrand and the interpretation of the integral in terms of physical concepts.

Discussion Status

The discussion is active, with participants providing insights into the mathematical formulation and physical interpretation of the integral. Some participants have offered clarifications on the relationship between the variables involved, while others are questioning the assumptions regarding proportionality within the integral.

Contextual Notes

There is some ambiguity regarding which variable is considered proportional to the integrand, and participants are seeking to clarify this aspect. The discussion also reflects a learning environment where notation and conceptual understanding are being examined.

Anti Hydrogen
Messages
37
Reaction score
4
Homework Statement
Hi, I'm trying to understand the case when a variable is proportional to that which is under a integral sign, for example
$$\Delta V = - \int_a^b \vec E \cdot d \vec s$$

What could be a interpretation of this equation?
Relevant Equations
Thanks
Thanks
 
Physics news on Phys.org
Anti Hydrogen said:
Homework Statement:: Hi, I'm trying to understand the case when a variable is proportional to that which is under a integral sign, for example
$$\Delta V = - \int_a^b \vec E \cdot d \vec s$$

What could be a interpretation of this equation?
Relevant Equations:: Thanks

Thanks
An integral is the limit of a summation process. Here we have ##\Delta V## as (the sum of) the product of the electric field multiplied by a length. You could compare this with:
$$W = \int_a^b \vec F \cdot d \vec r$$
 
Essentially this is a restatement what @PeroK was saying: consider the change in the potential ##\delta V## along a small displacement vector ##\delta \vec{r}## in a region where the electric field is ##\vec{E}##, $$\delta V = -\vec{E} \cdot \delta \vec{r}$$Now if we sum up all of these small changes along some path $$\sum \delta V = -\sum \vec{E} \cdot \delta \vec{r}$$If you now take the limit as the length of the displacement vector approaches zero, that is ##\delta \vec{r} \rightarrow d\vec{r}## and consequently also ##\delta V \rightarrow dV##, the sums turn into integrals $$\int_{V_{1}}^{V_{2}} dV = -\int_{a}^{b} \vec{E} \cdot d\vec{r}$$Apologies if I abused any notation! For this specific integral, the interpretation is the change in potential going from ##a## to ##b##.
 
  • Like
Likes   Reactions: PeroK
Anti Hydrogen said:
Homework Statement:: Hi, I'm trying to understand the case when a variable is proportional to that which is under a integral sign, for example
$$\Delta V = - \int_a^b \vec E \cdot d \vec s$$

What could be a interpretation of this equation?
Relevant Equations:: Thanks

Thanks
What variable is proportional to what under the integral sign? Are you saying that ##\Delta V## is proportional to ##\vec E \cdot d \vec s?## @PeroK said it right, look at the line integral as a summation.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 5 ·
Replies
5
Views
944
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 22 ·
Replies
22
Views
2K
Replies
2
Views
1K
  • · Replies 10 ·
Replies
10
Views
955
  • · Replies 6 ·
Replies
6
Views
2K