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

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

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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. Locate the 5 V source, the left series chain and the right parallel branches. Point at the source.
    You will see
    The source reads 5 V. Each side contains three 1 kΩ resistors, with separate ammeters on its feed.
    Why it matters
    Both networks share one supply so you can compare their resistance rules under the same voltage.

  2. Step 2

    Do
    Point at the left feed ammeter, the short horizontal arrow above the series resistors.
    You will see
    The series ammeter reads about 1.667 mA: 5 V / (1000 + 1000 + 1000) Ω.
    Why it matters
    The same current passes through every resistor in one path. Adding series resistance reduces that current.

  3. Step 3

    Do
    Read the voltmeter beside the lowest series resistor. Point at that resistor to compare its voltage readout.
    You will see
    The voltmeter shows about 1.667 V across that 1 kΩ resistor.
    Why it matters
    Three equal resistors share 5 V equally. This is the divider rule used in the host chapter.

  4. Step 4

    Do
    Point at the right feed ammeter, the arrow on the top wire leading to the parallel network.
    You will see
    The parallel network draws 15 mA in total, compared with 1.667 mA for the series chain.
    Why it matters
    Three parallel 1 kΩ resistors give about 333.3 Ω. The source supplies the sum of their branch currents.

  5. Step 5

    Do
    Point at the rightmost 1 kΩ resistor in the parallel network and inspect voltage and current.
    You will see
    Its readout shows 5 V and 5 mA. The other two equal branches also carry 5 mA each.
    Why it matters
    Parallel branches see the same voltage. Their currents add: 5 + 5 + 5 = 15 mA.

  6. Step 6

    Do
    Double-click the rightmost parallel resistor, change Resistance to 2200 Ω, and confirm. Point at that resistor again.
    You will see
    The changed branch keeps 5 V but its current falls to about 2.273 mA. The right feed ammeter falls to about 12.273 mA.
    Why it matters
    The larger resistance changes its own branch current. The other parallel branches still see the full supply.

  7. Step 7

    Do
    Double-click the rightmost resistor and restore 1000 Ω. Point at the right feed ammeter and compare with your first reading.
    You will see
    The parallel feed returns to 15 mA. The series ammeter still reads about 1.667 mA.
    Why it matters
    Restoring the original value checks repeatability. Use voltage, current and resistance together before accepting a circuit measurement.

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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