AC Circuits: Resistor, Capacitor & Inductor
Change frequency and components and see voltage, current, phase and impedance in an AC circuit.
Choose a component and change the frequency. In a resistor voltage and current move together, in a capacitor the current leads, in an inductor it lags.
About the AC Circuits: Resistor, Capacitor & Inductor
Free ac circuits: resistor, capacitor & inductor. Change frequency and components and see voltage, current, phase and impedance in an AC circuit. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for physics, the ac circuits: resistor, capacitor & inductor runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Change frequency and components and see voltage, current, phase and impedance in an AC circuit. Use it to explore physics ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the AC Circuits: Resistor, Capacitor & Inductor
- Use the controls to change Component, Frequency, Voltage amplitude, Resistance, Capacitance, and more. The simulation reacts instantly.
- Pick an option such as Resistor, Capacitor, Inductor, Series RLC to switch modes or load an example.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Compare a capacitor at 20 Hz and 400 Hz.
- Try the inductor.
- Choose series RLC and find resonance.
Key ideas you can learn
- In a resistor, current and voltage are in phase.
- In a capacitor the current leads the voltage by 90°.
- In an inductor the current lags by 90°.
- Impedance Z combines R, X_L and X_C.
Where this is used in the real world
Radios, filters, power grids and phone chargers all use AC circuit behaviour.
Who is this simulation for?
Physics students in middle school, high school and first-year university, teachers who want a quick demonstration for the projector, and anyone revising for exams. It works well for flipped classrooms because students can explore before the lesson.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
What is reactance?
The opposition of a capacitor or inductor to alternating current: X_C = 1/(ωC), X_L = ωL.
What is a phasor?
A rotating arrow that represents a sine wave's size and phase.
Is the AC Circuits: Resistor, Capacitor & Inductor free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the AC Circuits: Resistor, Capacitor & Inductor work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.