Answer:
t = 1.10 h
Step-by-step explanation:
For this exercise we must calculate the intensity that reaches the cell with the polarizers, for this we use Malus's law
I = I₀ cos² θ
Let's calculate
I = I₀ cos² 60
I = I₀ 0.907
This is the intensity that reaches the cell
To find time, use an inverse proportion rule or rule of three, the intensity Io in
t = I₀ / (0.907 I₀) 1 h
t = 1.10 h