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Unformatted text preview: From determining the differential electric field and integrating we find 0
From symmetry we could have also seen
that the net field in the ydirection must
π
be 0
kλ Ey = − θ E d R dq=λdl d y dl Physics 2B  Summer Session 2  C. Palmer ∫ 2
π
−
2 y x sin (θ ) dθ = 0
Charge Density +λ (C/m) August 7, 2013 9 If only half of the line of charge is infinite,
what would the total field in the ydirection be?
kE λ
A)
B)
Ey = −
Ey = 0
C) kE λ
Ey =
d
θ D) R x y d
kE λ
Ey = 2
d Charge dq=λdl d
y z dl Physics 2B  Summer Session 2 
C. Palmer Density +λ (C/m) August 7, 2013 10 If only half of the line of charge is infinite,
what would the total field in the ydirection be?
kE λ
A)
B)
Ey = −
Ey = 0
C) kE λ
Ey =
d
θ D) R x y d
kE λ
Ey = 2
d Charge dq=λdl d
y z dl Physics 2B  Summer Session 2  C. Palmer Density +λ (C/m) August 7, 2013 11 z There is a ring of charge, Q, in the z=0 plane.
Above the center of the ring at distance z, we x would like to know the value of the electric
field.
The ring has radius, R0.
R y z R0 Physics 2B  Summer Session 2  C. Palmer August 7, 2013 12 z The ring has radius, R0. What is the charge
density of the ring?
A) QC
σ=
2
2
π R0 m
C) QC
λ=
2π R0 m x y B) QC
σ=
π R2 m 2 D) QC
λ=
2π R m Physics 2B  Summer Session 2  C. Palmer R z R0 August 7, 2013 13 z The ring has radius, R0. What is the charge
density of the ring?
A) QC
σ=
2
2
π R0 m
C) QC
λ=
2π R0 m x y B) QC
σ=
π R2 m 2 D) QC
λ=
2π R m Physics 2B  Summer Session 2  C. Palmer R z R0 August 7, 2013 14 z There is a ring of charge, Q, in the z=0 plane.
The ring has radius, R0. x dEz y dE dER The dE has been added.
Think about what is going on with the radial component. θ
R dq=λdl Physics 2B  Summer Session 2  C. Palmer z R0 August 7, 2013 15 z There is a ring of charge, Q, in the z=0 plane.
The ring has radius, R0. x dEz dE dER The dE has been added.
The radial component will sum to zero because there will be complementary
θ
piece opposite it.
R
Again we only need to worry about the zcomponent
dq=λdl y z R0 Physics 2B  Summer Session 2  C. Palmer August 7, 2013 16 z There is a ring of charge, Q, in the z=0 plane.
The ring has radius, R0. x dEz dE dER Set up dEz quantitatively kE dq
dEz = cos (θ ) 2
R
kE dq
= cos (θ ) 2 2
R0 + z y θ
R dq=λdl Physics 2B  Summer Session 2  C. Palmer z R0 August 7, 2013 17 z There is a ring of charge, Q, in the z=0 plane.
The ring has radius, R0. x dEz dE dER Set up dEz quantitatively kE dq
dEz = cos (θ ) 2 2
R0 + z
z kE dq
=
2
2 R2 + z2
R0 + z 0
dq=λdl P...
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This note was uploaded on 09/10/2013 for the course PHYS 2B 2b taught by Professor Hirsch during the Summer '10 term at UCSD.
 Summer '10
 Hirsch

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