Effect of rotating polarizer on intensity of transmitted light

[NihalRi]

Homework Statement

Plane polarised is incident normally on a polerizer which can rotate in plane perpendicular to light. The intensity of of incident light is 8W[m][/-2] and transmitted intensity is 2W[m][/-2] if polerizer is rotated 90 deg what is the new transmitted intensity

Homework Equations

The Attempt at a Solution

Root of (8 squared minus 2 squared)=root 60
Resolving vectors?
Answer was 6W[m][/-2]
Which is just eight minus two, help? I don't know why

 

[gneill]

What is the law for polarizers? In other words, what relevant equation applies to polarizers?

 

[NihalRi]

What is the law for polarizers? In other words, what relevant equation applies to polarizers?

Transmitted intensity = incident intensity times cosine there
Where theta is the angle between the direction of the polerizer and the polarised light

 

[gneill]

Transmitted intensity = incident intensity times cosine there
Where theta is the angle between the direction of the polerizer and the polarised light

Close, but not quite: the cosine should be squared. Look up "Law of Malus" (or Malus's Law).