Key relationship
I₁=I₀/2 for unpolarized light; I₂=I₁cos²θ; tan iB=n₂/n₁.
Physics · Class 12
Polarizers and Brewster angle
The first polarizer selects a transverse direction. The analyzer passes the squared projection along its axis. At Brewster incidence, reflected and refracted rays are perpendicular and the reflected light is linearly polarized.
Open the interactive experiment →Polarizers and Brewster angle
முதல் துருவிப்பான் ஒரு அதிர்வு திசையைத் தேர்ந்தெடுக்கும். இரண்டாவதில் ஒளிச்செறிவு cos²θ விதியைப் பின்பற்றும்.
Key notes, relationships and model limits
Remember
The first polarizer selects a transverse direction. The analyzer passes the squared projection along its axis. At Brewster incidence, reflected and refracted rays are perpendicular and the reflected light is linearly polarized.
Common trap
The I₀/2 step applies to unpolarized input, not every incident polarization.
Model limits
Ideal polarizers; unpolarized incoming light; Brewster angle uses air-to-medium incidence and is independent of the analyzer setting.
What you will learn
Apply Malus and Brewster laws with their different angle definitions.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
Input100 gives50 after the first polarizer and25 at45°.
Why this matters
The model connects polarizers and brewster angle with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
Crossed ideal polarizers transmit?
- Half the incident light
- Zero
- All light
Read the explanation
Their axes differ by90°, so cos²90°=0.
Course connection: Class XII Chapter 10. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.