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Equivalent resistance (series + parallel)

Basic Electrical Lab · free online experiment, runs in your browser with no install or sign-up.

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Objective

Find the equivalent resistance of R1 in series with (R2 ∥ R3) from the source current.

Procedure

  1. Run and compare the source current with 10 V / Req.
  2. Change R3 to 1 kΩ and recompute Req.

Theory

Req = R1 + R2·R3/(R2+R3) = 1 kΩ + 2 kΩ ∥ 2 kΩ = 2 kΩ, so a 10 V source supplies 5 mA.

Questions to answer

  1. Which resistor dissipates most power?

Components used

Battery / DC source, 3 × Resistor 220 ohm 1/4W

About the model

Ideal wires; component models as listed in the catalogue (no parasitics, no temperature drift). Built without a breadboard so the schematic stays readable.

Open this experiment in the circuit simulator

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