3. (a) Write down the differential form of Maxwell's four equations.
Show that by taking the curl of both sides of Faraday's Law (Maxwell's third equation), a wave equation of the form
∇²Ē = (1/v²)(∂²Ē/∂t²)
can be derived for the electric field in free space.
Calculate v, the speed of the wave.
[You may use that for a vector field Ā, ∇ × (∇ × Ā) = ∇(∇ · Ā) − ∇²Ā.]
(b) Briefly explain why transmission lines must be used for high-frequency power transmission.
(c) Give two examples of transmission lines. In what everyday application might each be used?