The switch is closed. Rank the brightness of the bulbs.

A) A = B > C

B) A > B > C

C) A > B = C

D) A = B = C

E) Other

Solution: C. When the switch is closed, B and C are in parallel. So they must have the same electric potential difference and therefore the same power. The current through A gets split evenly between B and C, so it has twice the current. So it has greater power.