Does anybody know of a white material that changes to black when an electric current is introduced

I'm working on a clock where I would cut the numbers out of said material, and have an arduino vary the amount of current sent to the material to make the present time black and then a gradient to white as the value gets further away from the present, if that makes any sense. Basically i need a material that I can cut which gets darker as I send more current through it.

Yes, it is called the passive matrix LCD. That is what is put to use by old-fashioned digit displays. The neutral color isn't white, but rather a pale grayish green color.

Good, Gintable came up with a legitimate answer, because I was going to make a joke kind of.

For example you could take a white material, like a Caucasian, and introduce enough electric current to him/her and you will definitely get a crispy black Caucasian in no time