Gradient of scalar function discontinuous on boundary

AI Thread Summary
The discussion centers on the behavior of a scalar function g(r) that is constant within a volume 'v' but exhibits discontinuity at its boundaries, quantified by a constant 'M'. It is argued that the integral of the gradient of g(r) over the volume is zero, despite the discontinuity, unless the discontinuity approaches infinity. The correctness of equating the second integral to the third integral is affirmed. The implications of these integrals on the analysis of discontinuities in scalar functions are explored. Overall, the mathematical treatment of discontinuities in scalar functions is clarified.
mfurqan
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suppose g(r) is a scalar function which is constant inside the volume 'v' but discontinuous at the boundaries of 'v'. The magnitude of discontinuity is given by constant 'M' then can we write the following expression
\int\nablag(r)dv=M\int\hat{n}\delta(r-rs)dv=M\hat{n}\intd\deltav

where \deltav is the boundary of volume 'v'
rs\in\deltav
\hat{n} is the outward normal
 
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I think your first integral is zero, even though there is a discontinuity at the boundary. The only possible way that your first integral could be non-zero is if the discontinuity jumped to infinity.

As for your second integral equaling your third integral, that's correct.
 
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