Yes, learning should be based primarily on understanding rather than memorization and semiconductor science and engineering is no exception in this regard.

Still, there are things worth memorizing. Here is an example concerned with a simple relation converting wavelength of light to energy and vice versa. It comes very handy when interactions of light with semiconductors (absorption, emission, etc.) are of interest.

It starts with the titans of solid state physics, Max Planck and Albert Einstein and their formulation of a simple relation linking energy *E*** **and frequency *ν* of light ** E = h ν ** where

*h*is a Planck constant. It is enough to recall now that the frequency

**where**

*ν*= c/λ*c*is a speed of light in vacuum and

*λ*the light’s wavelength or the length of the wave of light. So,

**and with**

*E (eV)= h**c/*λ*h*and

*c*being constants we end up with a convenient formula

**used to convert wavelength of light to energy and vice versa. Actually, with**

*E (eV)=*1.24/ λ (*μm*)*E~1/λ*

*relation being rather obvious, what needs to be remembered is a proportionality factor*

**1.24**.