Gauss' Law for electric fields The electric field due to a point Q r 4TE, |r|3" charge Q is E where r = (x, y, z), and ɛ, is a constant. a. Show that the flux of the field across a sphere of radius a cen- tered at the origin is ,E -n dS = º. b. Let S be the boundary of the region between two spheres cen- tered at the origin of radius a and b, respectively, with a < b. Use the Divergence Theorem to show that the net outward flux across S is zero. c. Suppose there is a distribution of charge within a region D. Let q(x, y, z) be the charge density (charge per unit volume). Interpret the statement that || E·n ds =- q(x, y, z) dV. d. Assuming E satisfies the conditions of the Divergence Theorem on D, conclude from part (c) that V · E = 4. e. Because the electric force is conservative, it has a potential function o. From part (d), conclude that v²p = V • Vọ = 03

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Gauss' Law for electric fields The electric field due to a point
Q r
4TE, |r|3"
charge Q is E
where r = (x, y, z), and ɛ, is a
constant.
a. Show that the flux of the field across a sphere of radius a cen-
tered at the origin is ,E -n dS = º.
b. Let S be the boundary of the region between two spheres cen-
tered at the origin of radius a and b, respectively, with a < b.
Use the Divergence Theorem to show that the net outward flux
across S is zero.
c. Suppose there is a distribution of charge within a region D.
Let q(x, y, z) be the charge density (charge per unit volume).
Interpret the statement that
||
E·n ds =- q(x, y, z) dV.
d. Assuming E satisfies the conditions of the Divergence
Theorem on D, conclude from part (c) that V · E = 4.
e. Because the electric force is conservative, it has a potential
function o. From part (d), conclude that v²p = V • Vọ =
03
Transcribed Image Text:Gauss' Law for electric fields The electric field due to a point Q r 4TE, |r|3" charge Q is E where r = (x, y, z), and ɛ, is a constant. a. Show that the flux of the field across a sphere of radius a cen- tered at the origin is ,E -n dS = º. b. Let S be the boundary of the region between two spheres cen- tered at the origin of radius a and b, respectively, with a < b. Use the Divergence Theorem to show that the net outward flux across S is zero. c. Suppose there is a distribution of charge within a region D. Let q(x, y, z) be the charge density (charge per unit volume). Interpret the statement that || E·n ds =- q(x, y, z) dV. d. Assuming E satisfies the conditions of the Divergence Theorem on D, conclude from part (c) that V · E = 4. e. Because the electric force is conservative, it has a potential function o. From part (d), conclude that v²p = V • Vọ = 03
Expert Solution
Step 1

Step 1:

Given: The electric field due to a point charge is given by : E = Q4πεorr3 where r = x,y,z

Divergence Theorem : VFdV = SF.n dS 

Step 2

Step 2:

a) 

sE.n dS , we know n=r|r|.sE.n dS=sQ4πεorr3.r|r| dSsE.n dS=Q4πεosr2r4 dSsE.n dS=Q4πεos1r2 dSNote: Radius of sphere is a. Put r =a we get,sE.n dS=Q4πεos1a2 dSsE.n dS=Q4πεo1a2s dSsE.n dS=Q4πεo1a24πa2sE.n dS=Qεo

Step 3

Step 3:

b) 

According to Divergence theorem, 

VFdV = SF.n dS = S1F.n2 dS-S2F.n1 dSWe know that divergence of radial field F =r|r|p=3-p|r|pTherefore, ·F = 3-p|r|p ·F = 3-3|r|pfor p =3·F = 3-3|r|3·F = 0Now we want to find divergence of given electric field E = Q4πεorr3 where r = x,y,zV·EdV = SE.n dS ·E =·Q4πεor|r|3·E =Q4πεo·r|r|3·E = 0Therefore, D·E dV = D0.dV =0

Therefore, Net outward flux across the surface S is zero.

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