ENGINEERING NOTE
What does a phasor make visible?
From two sliders to the relationship between voltage and current.
In a series RL circuit, the resistor and inductor share the same current. The resistor voltage is in phase with that current, while the ideal inductor voltage leads it by 90 degrees. A phasor diagram shows the components in different directions.
The portfolio experiment fixes the supply at 230 V RMS and 50 Hz. Increasing inductance increases Xₗ = 2πfL. With resistance fixed, impedance rises, current falls and the phase angle grows. Set inductance to zero to obtain the pure-resistance example.
The total voltage is not the arithmetic sum of the resistor and inductor voltages: it is the vector sum of perpendicular components. This produces the voltage triangle. The power factor is the ratio of resistance to impedance.
This experiment is a standalone educational tool inspired by the MATLAB transmission-line project. It uses ideal sinusoidal steady-state calculations, rather than solving transient behaviour or electromagnetic fields.