# Effect of rotating polarizer on intensity of transmitted light

1. Jan 12, 2016

### NihalRi

1. The problem statement, all variables and given/known data

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
2. Relevant equations

3. The attempt at a solution
Root of (8 squared minus 2 squared)=root 60
Resolving vectors?
Which is just eight minus two, help? I dont know why

Last edited by a moderator: Jan 13, 2016
2. Jan 12, 2016

### Staff: Mentor

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

3. Jan 13, 2016

### NihalRi

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

4. Jan 13, 2016

### Staff: Mentor

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