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A linearly polarised electromagnetic wav...

A linearly polarised electromagnetic wave given as `E=E_(0)haticos(kz-omegat)` is incident normally on a perfectly reflecting wall `z=a`. Assuming that the material of the optically inactive, the reflected wave will be give as

A

`E_(r)=E_(0)hati(kz-omegat)`

B

`E_(r)=E_(0)haticos(kz-omegat)`

C

`E_(r)=-E_(0)haticos(kz-omegat)`

D

`E_(r)=E_(0)hatisin(kz+omegat)`

Text Solution

Verified by Experts

The correct Answer is:
B
When a wave is reflected from a denser medium or perfectly reflectinf wall made with optically inactive material then the type of wave doesn't change but only its phase changes by `180^(@)` or `pi` radian
Given here the incident electromagnetic eave is
`vecE=E_(0)(hati)cos(kz-omegat)`
This wave is incident normally on a perfectly reflecting infinite wall `z=a` Here the reflected wave in the direction of travelling of wave will be reversed and additional phase of `pi` in the incident wave
`vecE_(r)=E_(0)(hati)cos[k(-z)-omegat+pi]`
`=-E_(0)haticos[-(kz+omegat)+pi]`
`E_(0)haticos[-(kz+omegat)]=E_(0)haticos(kz+omegat)`
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