A multimeter is used to take a measurement as shown in the figure above. What will be the measured output?

Question

BlackTom AI · Accepted Answer

Current in a series circuit is the same through all elements, so the ammeter (inserted in series) reads the circuit current: I = V / R_total.

1) Relevant concepts
- An ideal ammeter is placed in series and measures circuit current.
- Series resistances add: R_total = R1 + R2.
- Ohm’s law: I = V / R.
- Unit conversions: 1 A = 1000 mA.

2) Step-by-step reasoning and calculations
- Resistors: 150 Ω and 50 Ω are in series, so R_total = 150 Ω + 50 Ω = 200 Ω.
- Supply voltage: V = 5.0 V.
- Using Ohm’s law: I = V / R_total = 5.0 V / 200 Ω.
- Compute: 5.0 / 200 = 0.025 A.
- Convert to milliamps: 0.025 A × 1000 mA/A = 25 mA.

3) Intermediate steps shown
- R_total = 150 + 50 = 200 Ω
- I (A) = 5 ÷ 200 = 0.025 A
- I (mA) = 0.025 × 1000 = 25 mA

4) Why the correct answer is correct
Because the meter is wired in series, it measures the single circuit current determined by the total resistance and the 5 V source. The calculation above directly yields 25 mA, so the meter will display 25 mA.

5) Why other choices are incorrect (brief)
- Values like 33 mA (≈5/150) or 100 mA (≈5/50) assume only one resistor in the path; both resistors are actually in series so these are wrong.
- Negative values would imply reversed meter polarity; the red lead is on the side receiving conventional current from the positive terminal, so the reading is positive.
- Options listed in volts (e.g., 3.75 V, 1.25 V) are voltage drops across individual resistors (3.75 V across 150 Ω, 1.25 V across 50 Ω) not the ammeter reading.

Conclusion: The measured output is 25 mA, confirming answer e. 25 mA.

A multimeter is used to take a measurement as shown in the figure above. What will be the measured output?单项选择题

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