Answers

1. Answer:

   Ok, the question is incomplete buy ill try to answer this in a general way.

   Suppose that you have no-polarized light.

   When that light hits one polaroid, the light becomes polarized along some line, and has an intensity I0.

   Now, when polarized light hits a polaroid which axis is at an angle θ with respect to the polarization of the light, the intensity of the resulting beam is given by the Malus’s law:

   I(θ) = I0*cos^2(θ)

   For example, if the axis of the polaroid is exactly the same as the one of the polarized light, then we have θ = 0°

   and:

   I(0°) = I0*cos^2(0°) = I0

   So the intensity does not change.

   Now, knowing the initial intensity, you can find the angle needed to get a given intensity.

   For example, if the question was:

   “At what angle should the axes of two Polaroids be placed so as to reduce the intensity of the incident unpolarized light to A”

   We should solve:

   I(θ) = A = I0*cos^2(θ)

   (A/i0) = cos^2(θ)

   √(A/I0) = cos(θ)

   Acos(√(A/I0)) = θ

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