# Chapter 31 - Electromagnetic Fields and Waves - Exercises and Problems - Page 903: 56

The light intensity after it emerges from the third filter is $~~0.125~I_0$

#### Work Step by Step

When unpolarized light passes through a polarizing filter, the intensity of the transmitted light is $0.5~I_0$ where $I_0$ is the original intensity. Thus the intensity is $I_1 = 0.5~I_0$ after passing through the first filter. We can find the intensity $I_2$ after passing through the second polarizing filter: $I_2 = I_1~cos^2~\theta$ $I_2 = 0.5~I_0~cos^2~45^{\circ}$ $I_2 = 0.25~I_0$ We can find the intensity $I_3$ after passing through the third polarizing filter: $I_3 = I_2~cos^2~\theta$ $I_3 = 0.25~I_0~cos^2~45^{\circ}$ $I_3 = 0.125~I_0$ The light intensity after it emerges from the third filter is $~~0.125~I_0$

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.