Measure series and parallel resistor circuits

Compare voltage and current in three-resistor series and parallel networks supplied from the same 5 V source.

Voltage Vera: I want you to predict the current before you read the meter., your practice guide

Voltage Vera: I want you to predict the current before you read the meter.
Predict the reading, then compare it with the measurement.

Falstad CircuitJS

Third party Tool

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Version tested: Falstad CircuitJS opened from the prepared ctz URL in Playwright Chromium 151.0.7922.34 on 2026-09-10; exported circuit and advancing simulation verified; no simulator version exposed. Date: 2026-09-10.

Open the prepared circuit.

Open this circuit in Falstad (new tab)

Steps

Screens captured against Falstad CircuitJS Falstad CircuitJS opened from the prepared ctz URL in Playwright Chromium 151.0.7922.34 on 2026-09-10; exported circuit and advancing simulation verified; no simulator version exposed on 2026-09-10; the tool may have moved on — the text steps are the contract.

  1. Step 1

    Do
    Open the prepared Falstad circuit. On the circuit canvas, locate the 5 V source, the left series chain and the right parallel branches. Point at the source.
    You will see
    Source panel: "Vd = 5 V". Series ammeter panel: "I = 1.667 mA". Series resistor panel: "Vd = 1.667 V"; "R = 1 kΩ". Parallel ammeter panel: "I = 15 mA". Right branch panel: "I = 5 mA"; "Vd = 5 V"; "R = 1 kΩ".
    Why it matters
    Expected: The source is 5 V; the series path is 3 kΩ and each parallel path is 1 kΩ. Meaning: One source lets both resistance arrangements be compared at the same voltage.

  2. Step 2

    Do
    On the Falstad circuit canvas, point at the left feed ammeter, the short horizontal arrow above the series resistors.
    You will see
    Source panel: "Vd = 5 V". Series ammeter panel: "I = 1.667 mA". Series resistor panel: "Vd = 1.667 V"; "R = 1 kΩ". Parallel ammeter panel: "I = 15 mA". Right branch panel: "I = 5 mA"; "Vd = 5 V"; "R = 1 kΩ".
    Why it matters
    Expected: 5 V / 3 kΩ = 1.667 mA through the series path. Meaning: Series resistances add, so the same small current passes all three resistors.

  3. Step 3

    Do
    On the Falstad circuit canvas, read the voltmeter beside the lowest series resistor. Point at that resistor to compare its voltage readout.
    You will see
    Source panel: "Vd = 5 V". Series ammeter panel: "I = 1.667 mA". Series resistor panel: "Vd = 1.667 V"; "R = 1 kΩ". Parallel ammeter panel: "I = 15 mA". Right branch panel: "I = 5 mA"; "Vd = 5 V"; "R = 1 kΩ".
    Why it matters
    Expected: 1.667 mA × 1 kΩ = 1.667 V across one series resistor. Meaning: The three equal voltage drops sum to the 5 V supply.

  4. Step 4

    Do
    On the Falstad circuit canvas, point at the right feed ammeter, the arrow on the top wire leading to the parallel network.
    You will see
    Source panel: "Vd = 5 V". Series ammeter panel: "I = 1.667 mA". Series resistor panel: "Vd = 1.667 V"; "R = 1 kΩ". Parallel ammeter panel: "I = 15 mA". Right branch panel: "I = 5 mA"; "Vd = 5 V"; "R = 1 kΩ".
    Why it matters
    Expected: Three 1 kΩ branches each draw 5 mA, totaling 15 mA. Meaning: The parallel network draws nine times the series-path current.

  5. Step 5

    Do
    On the Falstad circuit canvas, point at the rightmost 1 kΩ resistor in the parallel network and inspect voltage and current.
    You will see
    Source panel: "Vd = 5 V". Series ammeter panel: "I = 1.667 mA". Series resistor panel: "Vd = 1.667 V"; "R = 1 kΩ". Parallel ammeter panel: "I = 15 mA". Right branch panel: "I = 5 mA"; "Vd = 5 V"; "R = 1 kΩ".
    Why it matters
    Expected: 5 V / 1 kΩ = 5 mA in each equal parallel branch. Meaning: Each branch sees the full supply voltage.

  6. Step 6

    Do
    On the Falstad circuit canvas, double-click the rightmost parallel resistor, change Resistance to 2200 Ω, and confirm. Point at that resistor again.
    You will see
    Source panel: "Vd = 5 V". Series ammeter panel: "I = 1.667 mA". Series resistor panel: "Vd = 1.667 V"; "R = 1 kΩ". Parallel ammeter panel: "I = 12.273 mA". Right branch panel: "I = 2.273 mA"; "Vd = 5 V"; "R = 2.2 kΩ".
    Why it matters
    Expected: 5 V / 2.2 kΩ = 2.273 mA; 5 + 5 + 2.273 = 12.273 mA. Meaning: Changing one branch current changes the feed total while its voltage stays 5 V.

  7. Step 7

    Do
    On the Falstad circuit canvas, double-click the rightmost resistor and restore 1000 Ω. Point at the right feed ammeter and compare with your first reading.
    You will see
    Source panel: "Vd = 5 V". Series ammeter panel: "I = 1.667 mA". Series resistor panel: "Vd = 1.667 V"; "R = 1 kΩ". Parallel ammeter panel: "I = 15 mA". Right branch panel: "I = 5 mA"; "Vd = 5 V"; "R = 1 kΩ".
    Why it matters
    Expected: Restoring 1 kΩ makes the parallel total 15 mA again. Meaning: The unchanged series ammeter confirms the two arrangements share voltage, not current.

Chapter checks

These questions refer to the chapter’s examples. Use the return links to review their answers.

  1. A voltage divider uses 1kΩ (R1) and 3kΩ (R2) resistors to divide a 12V input. What is the output voltage across R2?

    Return to the chapter’s knowledge check

  2. Three resistors (100Ω, 220Ω, 330Ω) are connected in series. What is the total resistance?

    Return to the chapter’s knowledge check

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