🔖 Topics

  • Intensity
  • Polarizing filters
  • Linear polarization of light

🎯 Objectives

  • Describe the difference between unpolarized and polarized light
  • Calculate the intensity of light coming off of a polarizing filter

📋 Sequence

  • Definition of intensity - power per unit area
  • Unpolarized versus polarized light
  • Ideal polarizer
    • 50% of the intensity of unpolarized light passes through a polarizer
    • Malus’ law: \(I = I_o cos^2 \theta \)

🖥️ Animations, Simulations, Activities

📝 Practice Problems

  1. Unpolarized light is incident on a polarizing sheet oriented at \( 30^\circ \) with respect to the vertical. What percentage of the intensity of the light passees through the sheet?
  2. Unpolarized light is incident on two polarizing sheets in series. The sheets are oriented at \( 30^\circ \) with respect to each other. What percentage of the intensity of the light passes through the sheets?
  3. Unpolarized light is incident on four polarizing sheets in series. The sheets are oriented at \( 0^\circ \), \( 30^\circ \), \( 60^\circ \), and \( 90^\circ \) with respect to the vertical. What percentage of the intensity of the light passes through the sheets?
  4. Suppose I removed the \( 30^\circ \) and \( 60^\circ \) polarizers in the previous problem, leaving on the \( 0^\circ \) and \( 90^\circ \) polarizers in the diagram above. What percentage of the initial light intensity is transmitted through this new set of polarizers?

✅ Partial Solutions

  1. 50.0%
  2. 37.5%
  3. 21.0%
  4. 0.0%

📘 Connected Resources

  • ehtelescope. What Is Polarization? \Textbar Event Horizon Telescope. March 2021.
  • Giambattista, Alan, et al. College Physics With an Integrated Approach to Forces and Kinematics. 5th ed., McGraw-Hill Education, 2020.