add more on polar graphing

diff --git a/physics/waves.md b/physics/waves.md
index 0b085c54916e158887f49f38f35fb53fdad2e629..f082d0f2d326fcfd98548cb701852bbc9341f0f1 100644 (file)
--- a/physics/waves.md
+++ b/physics/waves.md
@@ -90,6 +90,8 @@ $f = {nv \div 4l}\quad$ (frequency for $n_{th}$ harmonic at length $l$ and speed
 
 ## Light
 
+
+
 Newton - light as a particle
 - light speeds up as it travels through a solid medium
 
@@ -106,7 +108,7 @@ $\Delta v$ depends on $\lambda$, so wavelengths become "split"
 ![](/mnt/andrew/graphics/refraction.png)
 
 Refractive index of a medium depends $\Delta v$ from $c$
-$n={c \over v}\quad$ (refractive index of a medium)
+$n={c \over v}\quad$ (refractive index of  poop medium)
 $n_1v_1=n_2v_2$ (equivalence between media)
 
 ### Snell's law
@@ -122,3 +124,11 @@ $n_1 sin \theta_c = n_2 \sin 90^\circ$
 $\therefore \theta_c = {n_2 \over n_1}$
 
 ### Dispersion
+
+### Double Slit
+
+- parallel slits of thickness comparable to $\lambda$
+- multiple wave fronts combine to form constructive / destructive interference
+- fringes - points of constructive interference
+- bright spot in centre of slits
+- solve path difference using pythag