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A more elegant proof of the second uniqueness theorem uses Green's

identity (Prob. 1.61c), with T=U=V3. Supply the details.

Short Answer

Expert verified

Answer

It is proved as second uniqueness of theorem by using greens identity.

Step by step solution

01

Define function

Write the Greens identity.

∫~NT~N2U+~NU×~NT»åÏ„=∮T~NU×da…… (1)

Given that T=U=V3,

Therefore, the greens identity is changes as,

∫~NV3~N2V3+~NV3×~NV3»åÏ„=∮V3~NV3×da …… (2)

02

Determine proof of Greens identity

Since

∇2V3=∇2V1-∇2V2∇2V1=-ÒÏε0∇2V2=-ÒÏε0

Then,

∇2V3=-ÒÏε0+ÒÏε0=0

As known to us,

∇V3=E3

E3=∇V3as per derivation.

03

Determine proof of Greens identity

Substitute the above values in equation (1)

∫∇V30+E32dτ=-∮V3E3·da∫∇E32dτ=-∮V3E3·da …… (3)

As,

E3=E1-E2 …… (4)

If V is specified as V3=0or E3=0then,

The equation (4) will be,

0=E1-E2E1=E2

Thus, filed is uniquely determined.

And it is proved as this is a second uniqueness theorem.

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Most popular questions from this chapter

A rectangular pipe, running parallel to the z-axis (from -∞to +∞), has three grounded metal sides, at y=0,y=aand x=0The fourth side, at x=b, is maintained at a specified potential V0(y).

(a) Develop a general formula for the potential inside the pipe.

(b) Find the potential explicitly, for the case V0(y)=V0(a constant).

Charge density

σ(ϕ)=asin(5ϕ)

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(a) Show that the quadrupole term in the multipole expansion can be written as

V"quad"(r⃗)=14πε01r3∑(i,j=13r^ir^jQij     .....(1)

(in the notation of Eq. 1.31) where

localid="1658485520347" Qij=12∫[3ri'rj'-(r')2δij]ÒÏ(r⃗')dÏ„'     .....(2)

Here

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localid="1658485969560" Vmon=14πε0Qr;Vdip=14πε0∑r^ipjr2;Vquad(r⇶Ä)=14πε01r3∑i,j=13r^ir^jQIJ;...

The monopole moment localid="1658485018381" (Q) is a scalar, the dipole moment localid="1658485022577" (p⇶Ä) is a vector, the quadrupole moment localid="1658485026647" (Qij)is a second rank tensor, and so on.

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(d) How would you define the octopole moment? Express the octopole term in the multipole expansion in terms of the octopole moment.

A charge is distributed uniformly along the z axis from z=-atoz=+a. Show that the electric potential at a point r is given by

Vr,θ=Q4πε01r1+13ar2P2cosθ+15ar4P4cosθ+...

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In Prob. 2.25, you found the potential on the axis of a uniformly charged disk:

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