- #1
htg
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Consider a lens of diameter d and a focal length f >> d.
Let the cross-section area of the lens be S = N*λ^2.
Let a plane wave be focused from S to an area S1=λ^2.
Then, by the linear superposition principle the electric field intensity
in the area S1 will be N times greater than it was in the original plane wave.
This means EM wave intensity N^2 times greater in the area S1,
which means N-fold increase of the power of the EM wave due to focusing.
Is focusing a process that violates energy conservation?
Let the cross-section area of the lens be S = N*λ^2.
Let a plane wave be focused from S to an area S1=λ^2.
Then, by the linear superposition principle the electric field intensity
in the area S1 will be N times greater than it was in the original plane wave.
This means EM wave intensity N^2 times greater in the area S1,
which means N-fold increase of the power of the EM wave due to focusing.
Is focusing a process that violates energy conservation?