Students are experimenting with circuits in their physics class, and they build the two working circuits pictured below. The battery in each circuit is identical, and each bulb
(resistor) they add provides the same amount of resistance.
Circuit A
Circuit B
RI
R2
RE
H
W
w
They notice that every time they added bulb 3 (R3) to circuit A, the brightness of all
the bulbs dimmed, but when they added bulb 3 (R3) to circuit B, there is no change
to the brightness. Which explanation of this observation is most complete?