{\bf Angular momentum of EM fields} \[ @@ -1628,7 +1628,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
{\bf Continuity equation} \[ @@ -1658,7 +1658,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
This is thus simply a conservation law for momentum, with
-{\bf Momentum density in the EM fields} \[ @@ -1624,7 +1624,7 @@ This is thus simply a conservation law for momentum, with
In a region in which the mechanical momentum is not changing due to external influences, we then have the
-{\bf Continuity equation for EM momentum} \[ @@ -1651,7 +1651,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
This expression can be greatly simplified by introducing the
-{\bf Maxwell stress tensor} \[ @@ -1677,7 +1677,7 @@ The element \(T_{ij}\) represents the force per unit area in the $i$th direction
We then obtain
-{\bf EM force per unit volume} \[ @@ -1689,7 +1689,7 @@ We then obtain
where \({\boldsymbol S}\) is the Poynting vector. Integrating, we obtain the
-{\bf Total force on charges in volume} \[ @@ -1716,7 +1716,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
{\bf Poynting's theorem} \[ @@ -1691,7 +1691,7 @@ energy is carried by EM fields out of \({\cal V}\) across its boundary surface.
Energy per unit time, per unit area carried by EM fields:
-{\bf Poynting vector} \[ @@ -1704,7 +1704,7 @@ Energy per unit time, per unit area carried by EM fields:
We can thus express Poynting's theorem more compactly:
-{\bf Poynting's theorem} \[ @@ -1717,7 +1717,7 @@ We can thus express Poynting's theorem more compactly:
where we have defined the total
-{\bf Energy in electromagnetic fields} \[ @@ -1740,7 +1740,7 @@ Then, \] so we get the
-{\bf Poynting theorem (differential form)} \[ @@ -1757,7 +1757,7 @@ and has a similar for to the continuity equation -
\paragraph{Example 8.1} Current in a wire: Joule heating. Energy per unit time delivered to wire: from Poynting. Assuming that the field is uniform, the electric field parallel to the wire is @@ -1800,7 +1800,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
+
+
Prerequisites
@@ -1608,8 +1608,8 @@ Prerequisites
-
-
+
+
Objectives
@@ -1648,7 +1648,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Prerequisites
-
@@ -1608,8 +1608,8 @@ Prerequisites
+
+
Objectives
@@ -1648,7 +1648,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Objectives
-
@@ -1648,7 +1648,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
{\bf Poynting vector of a monochromatic EM wave} \[ @@ -1644,7 +1644,7 @@ This has a transparent physical interpretation: the energy density \(u\) flows w
Similary, we get the
-{\bf Momentum density of a monochromatic EM wave} \[ @@ -1693,7 +1693,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
{\bf E and B fields for a monochromatic EM plane wave} \[ @@ -1671,7 +1671,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
{\bf Wave equations for electric and magnetic fields in vacuum} \[ @@ -1680,7 +1680,7 @@ target="_blank">Creative Commons Attribution 4.0 International License.
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
Created: 2022-02-09 Wed 22:40
+Created: 2022-02-10 Thu 08:32
{\bf Polarization current density} \[ @@ -1651,7 +1651,7 @@ the polarization current is the result of linear motion of charge when polarization changes). We can check consistency with the continuity equation associated to the conservation of bound charges:
-