Light and Optics

This page provides a key to interpreting symbols and units in Introductory Electricity & Magnetism, and provides values of constants in SI units.

Light and Matter

Light reflects off a surface at an angle equal to its incident angle (Law of reflection):

$$ \theta_{incident}=\theta_{reflected} $$

The speed of an EM wave changes when it travels through matter. The index of refraction n tells us how much:

$$ v=\frac{c}{n} $$

EM waves bend when they change medium ('Snell's Law'):

$$ n_1\sin\theta_1=n_2\sin\theta_2 $$

Total internal reflection happens at the critical angle:

$$ \sin\theta_c=\frac{n_2}{n_1} $$

The sum of all angles in a triangle is 180 deg.

The sum of all angles in a quadrilateral is 360 deg.

The sum of all angles that make a line is 180 deg.

Something about parallel lines and angles

Something about similar triangles