NEET UG PHYSICS MCQ: ELECTROMAGNETIC WAVES

1 Medium

1 of 1

Analyzing +4 | -1

An EM wave from air enters a medium. The electric fields are

{E_1} = {E_{01}}\hat x\cos \left[ {2\pi v\left( {\frac{z}{c} - t} \right)} \right]

in air and

{E_2} = {E_{02}}\hat x\cos \left[ {k\left( {2z - ct} \right)} \right]

in medium, where the wave number k and frequency ν refer to their values in air. The medium is non-magnetic.
If

{\varepsilon _{{r_1}}}

and

{\varepsilon _{{r_2}}}

refer to relative permittivities of air and medium respectively, which of the following options is correct?

View answer and explanation

Correct option: C

\frac{{{\varepsilon _{{r_1}}}}}{{{\varepsilon _{{r_2}}}}} = \frac{1}{4}

Option C (

\frac{{{\varepsilon _{{r_1}}}}}{{{\varepsilon _{{r_2}}}}} = \frac{1}{4}

) is correct because the refractive index of the medium is 2, and the relative permittivity is related to the square of the refractive index.

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