What is the difference in potential between two charges called

Its potential is taken as zero potential. Thus the positively charged conductor has more positive potential than the earth. A  negatively charged conductor has negative potential less than that of the earth. The electric potential difference between two points in an electric circuit is the work done in moving a unit positive charge from one point to the other.

a motor homunculus represents a map of brain areas dedicated to motor processing for different anatomical divisions of the body.

homunculus represents the importance of various parts of your body as seen by your brain. as a result, they take up a lot of brain space. although the cortical homunculus is a curiosity, penfield's work in mapping the brain's relationship to the body was invaluable.

the electromagnetic energy from the sun arrives in the form of visible and invisible light.