Answer:
6.0 Ω
Explanation:
The equivalent resistance can be found with Ohm's law:
V = IR
12 V = (3.0 A) Rₑ
Rₑ = 4.0 Ω
For resistors in parallel, the equivalent resistance is:
1/Rₑ = 1/R₁ + 1/R₂
1/4.0 = 1/12 + 1/R
R = 6.0 Ω
The resistance of the unknown resistor is 6.0 Ω.
