Discharge is the act of removing or losing charge. If the velocity increases, the discharge would increase (i'm guessing that the width and depth of the area is increasing).
An inference is a conclusion reached on the basis of evidence and reasoning; because of this, then probably that.
Because the silvery mole rat has small eyes (and spends most of it's time underground), it can be inferred that its vision is poor. Therefore, "The animal likely has poor vision since its eyes are so small."
Is that the whole question please be more specific