Unpolarized light passes through two ideal Polaroid sheets. 12.3% of the incident light is transmitted. What is the angle between the transmission axes of the Polaroid sheets?

If I be the intensity of original light, after first polarization, its intensity becomes I/2

After second polarization its intensity becomes I/2 X Cos²θ

where θ is the angle between the two polaroids

So I₁ = I/2 Cos²θ

I₁ / I =.5 X Cos²θ = 0.123

Cos²θ = 0.246

θ = 60 degree. Ans