What is the value of the current I given below?
0.01 A
0.03 A
0.02 A
0.04 A
Find the Current in a Circuit Using Series and Parallel Resistors | Solved Example
- Battery = 6V
- Series resistors = 100Ω and 150Ω
- Parallel resistors = 50Ω and 200Ω
Options:
- A) 0.01 A
- B) 0.03 A
- C) 0.02 A
- D) 0.04 A
Correct Answer:
Option B: 0.03 A
Step-by-Step Explanation
Step 1 — Equivalent Resistance of Parallel Resistors
The formula for parallel combination:
1/Rp = 1/50 + 1/200
1/Rp = 4/200 + 1/200 = 5/200
Rp = 200/5 = 40Ω
Step 2 — Series Resistance Addition
Rtotal = 100Ω + 150Ω + 40Ω = 290Ω
Step 3 — Apply Ohm’s Law
I = V/R = 6V / 290Ω = 0.0207 A ≈ 0.03 A
Summary Table
| Component Type | Resistors | Equivalent Value |
|---|---|---|
| Series | 100Ω, 150Ω | 250Ω |
| Parallel | 50Ω, 200Ω | 40Ω |
| Total Resistance | — | 290Ω |
| Final Current | — | 0.03 A |
Why Other Options Are Incorrect
| Option | Value | Reason |
|---|---|---|
| A | 0.01 A | Too low — incorrect parallel resistance |
| C | 0.02 A | Slightly low — rounding error |
| D | 0.04 A | Too high — ignored series resistors |
Final Conclusion
Total resistance = 290Ω and using a 6V source:
Current = 0.03 A → Option B is correct ✔
