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 A light wave is incident normally on a glass slab of refractive index 1.5 . If 4% of light gets refelcted and the amplitude of the electric field of the incident light is 30 V/m, then the amplitude of the electric field for the wave propogating in the glass medium will be :

  • Option 1)

    6 V/m

  • Option 2)

     24 V/m

  • Option 3)

     10 V/m

  • Option 4)

     30 V/m

Answers (1)

best_answer

 

When Thermal Radiation(Q) fall in a body -

Q=Q_{a}+Q_{t}+Q_{r}

\frac{Q}{Q}=\frac{Q_{a}}{Q}+\frac{Q_{t}}{Q}+\frac{Q_{r}}{r}

1 = a + r + t

- wherein

\mu =1.5

For a wave

I=\frac{1}{2}\varepsilon _{0}E_{0}^{2}c

in medium

I=\frac{1}{2}\varepsilon E^{2}V

I^{2}=\left ( 1-0.04 \right ) I=0.96I

\Rightarrow \frac{1}{2}\varepsilon E^{2}V=0.96\times \frac{1}{2}\times \varepsilon _{0}E_{0}^{2}\times c

\Rightarrow E=\sqrt{0.96}\times \sqrt{\frac{\varepsilon _{0}}{\varepsilon }}\times \sqrt{\frac{C}{V}}\times E_{0}

 

\varepsilon =\varepsilon _{0}\varepsilon _{r}  & \mu =\sqrt{\mu _{r}\varepsilon _{r}},\mu =\frac{c}{v}

So E=\sqrt{0.96}\times \sqrt{\frac{\varepsilon _{0}}{\varepsilon_{0}\varepsilon _{r}}}\times \sqrt{\frac{C}{V}}\times E_{0}

 

=\sqrt{0.96}\times \frac{1}{\sqrt{\varepsilon _{r}}}\times \sqrt{\frac{C}{V}}\times E_{0}

Let \mu =1

So \mu =\sqrt{\varepsilon _{r}}

So E=\sqrt{0.96}\times \sqrt{\frac{1}{\varepsilon _{r}}}\times \sqrt{u}\times E_{0}

E=\sqrt{\frac{0.96}{\mu }} E_{0}=\sqrt{\frac{0.96}{1.5 }} E_{0}

E\approx 24\frac{V}{m}


Option 1)

6 V/m

Option 2)

 24 V/m

Option 3)

 10 V/m

Option 4)

 30 V/m

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