The depicted circuit contains four identical ohmic light bulbs, a switch, and a
ID: 1420638 • Letter: T
Question
The depicted circuit contains four identical ohmic light bulbs, a switch, and a voltage source. Currently, the switch is open. Which one of the following is true regarding the relative brightness ("greater than" denotes higher brightness of the bulb)? Now the switch is closed. Which one of the following is now true, compared to before it was closed? 1, 3, 4: dimmer than before 2: same as before 1: brighter than before 3, 4: same as before 2: off 1, 3, 4: same as before 2: brighter than before 1, 3, 4: same as before 2: off 1, 3, 4: brighter than before 2: off 1, 3, 4: dimmer than before 2: offExplanation / Answer
(1) second option 1=2>3=4 is correct
(2) after switch is closed, the bulb 2 will be short circuited. the resistance in the circuit decreases and current flow increases. thus, brightness of 1,2,3 increases.
ans: 1,2,3 brighter than before, 2 off is correct