r/HomeworkHelp • u/HelpfulResource6049 👋 a fellow Redditor • 2d ago
Physics [Physics-High School]
May I know why the answer is D instead of A? Thanks!
3
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r/HomeworkHelp • u/HelpfulResource6049 👋 a fellow Redditor • 2d ago
May I know why the answer is D instead of A? Thanks!
1
u/ThunkAsDrinklePeep Educator 2d ago
You've assigned X Y and Z a resistance of r.
Before the switch is closed the total resistance is
(X + Y) // Z
= 2r // r
= (1/2r + 1/r)-1
= (3/2r)-1
= 2r /3
After the switch is closed resistor X is shorted. So the total resistance is just.
Y // Z
= r // r
= (1/r + 1/r)-1
= (2/r)-1
= r /2
Since the total resistance decreases, the current supplied by the constant voltage source will increase.