An electron moves along the trajectory from i to f in as shown in
the figure to the right.
(a) Does the electric potential energy increase, decrease, or stay
the same? Explain.
(b) To trace out a trajectory like this, the electron must have
a nonzero initial velocity. What is its direction (Use a coordinate system where xˆ points towards the right, yˆ points
toward the top of the page and zˆ points out of the page).
(c) Is the electron’s speed at f greater than, less than, or equal
to its speed at i? Explain

An electron moves along the trajectory i to position f in Fig Q21.5

a) Does the electric potential energy increase, decrease, or stay the same?

b) Is the speed of the electron at f greater than, equal to or less than that in i?

An electron (q=-e) possesses a charge of  Q=+3e and it moves in a circular path in an orbit completing half of its radius r around a nucleus.

a. Calculate the amount of work done on the electron as it moves in the circular path from i to f (half of the circle). Justify your answer.

b. Calculate the change in electric potential energy change as the electron moves from i to f?

c. Measure the electron's speed at f (greater than, less than, or equal to its speed at i).