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Solve this problem Two Polaroids P1 and P2 are placed with their axis perpendicular to each other. Unpolarised light I0 is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its axis makes an angle 45° with that of P1 . Th

Two Polaroids P1 and P2 are placed with their axis perpendicular to each other. Unpolarised light I0 is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its axis makes an angle 45° with that of P1 . The intensity of transmitted light through P2 is:

  • Option 1)

    \frac{{\text{I}_0 }} {2}

  • Option 2)

    \frac{{\text{I}_0 }} {4}

  • Option 3)

    \frac{{\text{I}_0 }} {8}

  • Option 4)

    \frac{{\text{I}_0 }} {16}

 
Answers (1)
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As we learnt in

Malus Law -

I= I_{0}cdot cos ^{2}	heta

	heta = angle made by E vector with transmission axis.

- wherein

I= Intensity of transmitted light after polarisation .

I_{0}= Intensity of  incident light.

 

 

 

Intensity of light after crossing P_1=\frac{I_0}{2}

Intensity of light after crossing P_3=\frac{I_0}{2}.cos^245^{\circ}=\frac{I_0}{4}

Intensity of light after crossing  P_2=\frac{I_0}{4}.cos^245^{\circ}

I=\frac{I_0}{8}


Option 1)

\frac{{\text{I}_0 }} {2}

Incorrect

Option 2)

\frac{{\text{I}_0 }} {4}

Incorrect

Option 3)

\frac{{\text{I}_0 }} {8}

Correct

Option 4)

\frac{{\text{I}_0 }} {16}

Incorrect

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