Electrical circuits and water circuits both have?

What is the fate of the electrons that interact with a specimen in an electron microscope?

What is the force that opposes motion and works against the downward pull? a) friction b) gravity c) weight d) acceleration

According to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does maria's voyage take according to samir?