## Numerical Aperture (Definition)

` $$ A_{\text N} ~=~ \class{brown}{n} \, \sin(\class{gray}{\varphi}) $$ `

Learn how light can be described as a ray or wave and how you manipulate light with lasers and optical lenses.

` $$ A_{\text N} ~=~ \class{brown}{n} \, \sin(\class{gray}{\varphi}) $$ `

List of important physical quantities, their symbols, (derived) units and examples with images.

Learn about important physical constants and what their formula symbols and SI units are.

` $$ \varphi ~=~ \varphi_{\text r} $$ `

Here we derive the double-slit formula, which you can use, for example, to find the wavelength of light using a double-slit experiment.

` $$ \nu ~=~ \frac{1}{\lambda} $$ `

` $$ k ~=~ 2\pi \, \nu $$ `

` $$ k ~=~ \frac{2\pi}{\lambda} $$ `

` $$ \alpha_{\text c} ~=~ \arcsin\left( \frac{n_2}{n_1} \right) $$ `

` $$ n_1 \, \sin(\alpha_1) ~=~ \sin(\alpha_2) \, n_2 $$ `