Question 32
Current ElectricityIn the circuit diagram above, the ammeter reads a current of 3 A when R is 5 Ω and 6 A when R is 2 Ω. Determine the value of x.
- A.8 Ω
- B.2 Ω
- C.10 Ω
- D.4 Ω
Show the answer and explanation
Answer: C (10 Ω)
Explanation
R and x are in parallel across E: E = 3 × 5x/(5 + x) = 6 × 2x/(2 + x). So 15(2 + x) = 12(5 + x), giving 3x = 30 and x = 10 Ω.