From be63a1d882c0f9d09f218b87666a6c324c22fa84 Mon Sep 17 00:00:00 2001 From: eggy Date: Mon, 11 Jan 2021 19:08:43 -0500 Subject: [PATCH] phys: clarify intensity variables --- docs/sph3u7.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/sph3u7.md b/docs/sph3u7.md index fd04f2b..1f072ff 100644 --- a/docs/sph3u7.md +++ b/docs/sph3u7.md @@ -698,7 +698,7 @@ $$E\propto I\propto A^2$$ **Malus's law** states that for a polarised wave of energy $E_0$, the amplitude from the second filter, where $\theta$ is the angle between the polariser and the analyser, such that: $$E=E_0\cos\theta$$ -And so: +And so, where $I$ is the intensity of the polarised/analysed light, $I_0$ is the intensity of the plane-polarised light, and $\theta$ is the angle between the polariser and the analyser: $$I=I_0\cos^2\theta$$ When **unpolarised light** passes through a polariser, the average result of $I\cos^2\theta$ is $\frac{1}{2}$, so the intensity of polarised light is **half** of the intensity of unpolarised light.