Question 5
In that same parallel system, what current flows through the 12 Ω resistor?
The right answer is the one marked above.
0.5 A. The full 6 V is across the 12 Ω because both branches join the same two points, so I = 6 ÷ 12 = 0.5 A.
Notice you use 12 Ω here, not the 4 Ω equivalent. The equivalent resistance is for the whole system; a branch current uses that branch’s own resistance.