Lamp circuits in series and in parallel

Objective

Compare three identical lamps (100 Ω) in series and in parallel on a 12 V supply.

Procedure

1. Run and compare the brightness (LED current) of both groups.
2. Remove one lamp: in the series group everything goes dark, in the parallel group the others stay lit.

Theory

Series: the same current I = V/3R = 40 mA flows through all lamps, each gets V/3. Parallel: each lamp gets the full 12 V and draws 120 mA, so the supply delivers 360 mA.

Questions to answer

1. Why are house lamps wired in parallel?

Components used

Battery / DC source, 6 × 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.

More Basic Electrical Lab experiments

• Kirchhoff's current law
• Kirchhoff's voltage law
• Superposition theorem
• Thevenin's theorem
• Norton's theorem