Are there materials that can change the amount of light passing through? For example due to aligning their molecules or crystals differently?
In my materials book there are sometimes notes to some awesome materials. Like ones that change properties when electricity runs through them or that slowly transition into new structures due to heat.
So I was wondering if there are materials that have the property to change the amount of light passing through. For example that become more transparent or more opaque when a current runs through it, a magnet is used to change the alligning of the molecules/crystals or due to heat.