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 30° makes the two beams appear equally bright. If the initial intensities of the two beams are IA and IB respectively, then equals:

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Polarisation of Light New

Question

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 30° makes the two beams appear equally bright. If the initial intensities of the two beams are I_A and I_B respectively, then equals:

$\frac{3}{2}$

$\frac{1}{3}$

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I_A cos² 30° = I_B cos² 60°

$\frac{I_{A}}{I_{B}} = \frac{1}{3} \frac{I_{A}}{I_{B}} = \frac{1}{3} \frac{I_{A}}{I_{B}} = \frac{1}{3}$