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JEE Main PAPER - 1

JEE Main · 2018

180 questions · One at a time

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109
MCQ4 marks

An EM wave from air enters a medium. The electric fields are E1=E01x^cos[2πν(zct)]\vec{E}_1 = E_{01}\hat{x}\cos [2\pi \nu (\frac{z}{c} -t)]   in air and E2=E02x^cos[k(2zct)]\vec{E}_2 = E_{02}\hat{x}\cos [k(2z - ct)]   in medium, where the wave number kk   and frequency ν\nu   refer to their values in air. The medium is non-magnetic. If ϵr1\epsilon_{r1}   and ϵr2\epsilon_{r2}   refer to relative permittivities of air and medium respectively, which of the following options is correct?

  • A.ϵr1ϵr2=14\frac{\epsilon_{r1}}{\epsilon_{r2}} = \frac{1}{4}Correct
  • B.ϵr1ϵr2=12\frac{\epsilon_{r1}}{\epsilon_{r2}} = \frac{1}{2}
  • C.ϵr1ϵr2=4\frac{\epsilon_{r1}}{\epsilon_{r2}} = 4
  • D.ϵr1ϵr2=2\frac{\epsilon_{r1}}{\epsilon_{r2}} = 2
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