Beginner Fundamentals

Voltage Divider

Two resistors divide an input voltage proportionally. The output voltage depends on the ratio of the resistors.

// Voltage Divider

Simulator: Falstad CircuitJS1 (GPL-2.0) — hosted by falstad.com

Observe the voltage divider. The source provides 10 V across two resistors in series: R1 = 1 kΩ and R2 = 2 kΩ.

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The same current flows through both resistors because they are in series.
The output voltage (across R2) follows the divider formula: Vout = Vin × R2 / (R1 + R2). Calculate the expected Vout.

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Vout = 10 × 2000 / (1000 + 2000) = 10 × 2/3 ≈ 6.667 V
In the Falstad simulator, right-click R2 and change it to 1 kΩ. What does Vout become?

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Vout = 10 × 1000/2000 = 5 V. Equal resistors split the voltage equally.
Restore R2 to 2 kΩ, then change R1 to 500 Ω. How does this affect Vout?

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Vout = 10 × 2000/2500 = 8 V. Decreasing R1 raises the output voltage.

Expected values

Probe	Value	Unit
Vin	10	V
Vout	6.667	V