JEE Main 2018 — Electromagnetic Waves Question with Solution
From: JEE Main 2018 (Offline)
Question
An EM wave from air enters a medium. The electric fields are
= in air and
= in medium,
where the wave number k and frequency refer to their values in air. The medium is non-magnetic. If and refer to relative permittivities of air and medium respectively, which of the following options is correct ?
= in air and
= in medium,
where the wave number k and frequency refer to their values in air. The medium is non-magnetic. If and refer to relative permittivities of air and medium respectively, which of the following options is correct ?
Choose an option
Show full solutionCorrect option: C
Correct answer
C
Step-by-step explanation
Electric field in air,
= E01 cos ( 2vt )
Velocity in air = = c
Also, c = . . . . . . (1)
= E02 cos(2kz kct)
Velocity in medium = =
Also, = . . . . . (2)
As, medium is non magnetic,
So, medium = air =
Dividing (1) by (2), we get
2 =
=
= E01 cos ( 2vt )
Velocity in air = = c
Also, c = . . . . . . (1)
= E02 cos(2kz kct)
Velocity in medium = =
Also, = . . . . . (2)
As, medium is non magnetic,
So, medium = air =
Dividing (1) by (2), we get
2 =
=
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