Spherical Polar Coordinates
In EM it may be easier to express a problem within a “natural”
symmetry
x=r sin cos
y=r sin sin
z=r cos
r : [0,∞ ]; : [0, ] ; :[ 0,2 ]
Spherical Polar Coordinates
Spherical Line Element
sin d
d l=dr r r d r
Spherical Area Element
2
d a=d l dl r =r sin d d r
Spherical Volume
Element
2
d =dl r d l dl =r sin dr d d
Spherical Polar Coordinates
All the vector operators can be expressed in other coord
systems
∂T 1 ∂T 1 ∂T
∇ T= r
∂r r ∂ r sin ∂
1 ∂ 2 1 ∂ 1 ∂v
∇⋅v= 2
r v r sin v
r ∂r r sin ∂ d r sin ∂
∇ ×v=
1
r sin ∂[ ∂
sin v −
∂ v
∂ ] [
r
1
r sin
1
∂ vr
∂
−
∂
∂r ]
r v
[
1 ∂
r ∂r
r v −
]∂ vr
∂
Cylindrical Polar Coords
x=r cos 2
r= x y
2
y=r sin tan =y / x
z=z z=z
r : [0,∞ ]; : [0,2 ]; z :[−∞ , ∞]
Cylindrical Polar Coordinates
Line Element
d l=dr r r d d z z
Area Element
d a=r d dz r (wall)
d a=r dr d z (end)
Volume Element
d =r dr d d z
Cylindrical Polar Coordinates
1 ∂ T ∂T
∂T
∇ T= r z
∂r r ∂ ∂z
1 ∂ 1 ∂ v ∂ vz
∇⋅v= r v r
r dr r ∂ ∂z
∇ ×v=
[ 1 ∂ vz
r d
−
∂ v
∂z ][
r
∂ vr
∂z
−
∂ vz
∂ vr ] [
1 ∂
r ∂r
r v −
∂ vr
∂ ] z