Proof of Electromagnetic Identity: Puzzling Last Expression

AI Thread Summary
The discussion centers on understanding a specific expression in electromagnetics related to the line integral of dV. The user expresses confusion over why this integral equals zero and seeks clarification on its meaning, particularly when evaluated along a curve with defined endpoints. The conversation reveals that the integral can be expressed in terms of a parameterized curve, leading to further inquiries about the completeness of the explanation provided. Ultimately, the response indicates that the lack of completion was intentional to provoke deeper thought. The exchange highlights the complexities of interpreting electromagnetic identities and the nuances of mathematical expressions.
larginal
Messages
3
Reaction score
2
Homework Statement
two identities in electromagentics
Relevant Equations
curl of gradientV = 0
question.jpg

I tried to understand proof of this identity from electromagnetics. but I was puzzled at the last expression.
why is that line integral of dV = 0 ?
In fact, I'm wondering if this expression makes sense.
 
Last edited by a moderator:
Physics news on Phys.org
If you had a curve integral along a curve ##\Gamma## with endpoints ##p## and ##q##, what would the integral
$$
\int_\Gamma dV
$$
be? Note that
$$
\int_\Gamma dV = \int_0^1 \frac{dV}{dt} dt
$$
if we assume that ##t## is a curve parameter in the interval [0,1] parametrising the curve such that ##p = \Gamma(0)## and ##q = \Gamma(1)##.
 
  • Like
Likes JD_PM, docnet and etotheipi
I got it. Thanks! is it your intention that you didn't complete the explanation to make me think?
 
  • Like
Likes berkeman and etotheipi
larginal said:
is it your intention that you didn't complete the explanation to make me think?
Yes.
 
  • Like
Likes JD_PM, docnet, berkeman and 1 other person
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top