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 Two beams, A and B, of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam A has maximum intensity (and beam B has zero intensity), a rotation of polaroid through 300 makes the two beams appear equally bright. If the initial intensities of the two beams are IA and IB respectively, then \frac{I_{A}}{I_{B}}  equals ::


  • Option 1)


  • Option 2)


  • Option 3)


  • Option 4)



Answers (1)


As we learnt in

Malus Law -

I= I_{0}\cdot \cos ^{2}\theta

\theta = angle made by E vector with transmission axis.

- wherein

I= Intensity of transmitted light after polarisation .

I_{0}= Intensity of  incident light.


 We know that 


I_{A} \left(\frac{3}{4} \right )=I_{B} \left(\frac{1}{4} \right )

\therefore\ \; \frac{I_{A}}{I_{B}}=\frac{1}{3}

Correct option is 4.


Option 1)


This is an incorrect option.

Option 2)


This is an incorrect option.

Option 3)


This is an incorrect option.

Option 4)


This is the correct option.

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