Dust grains (r'= 1μm) in Saturn's rings are in a region of dilute ionized gas. Thus, these dust grains can pick up electrons. If the electric potential at the surface of a dust grainis400 V, determine the number of electrons on the surface of that dust grain. Assume thatthe electrons are distributed spherically and that the individual dust grains are far enoughapart that their electrons don't a ect each other.

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.