2. Rank the following in the order of how much of a corona discharge they would produce, from highest to least (e.g., if D is highest, then A, C, and B is lowest. enter DACB). Explain your response.
a. a large round metal ball hooked to a high voltage battery
b. a sharp metal needle connected by a wire to the ground (i. e. at zero voltage)
c. a large round metal ball hooked to a low voltage battery
d. a metal needle hooked to a high voltage battery