Is embedding the RC / RL circuit simulator free?

Yes. It is free to embed on any site, with no account, no API key and no usage limits. The whole simulation runs in your visitor’s own browser, so there is no server cost — we only ask that you keep the small "RC & RL Circuit Simulator by LK Forge" credit line that comes with the embed code.

What can visitors do with the embedded simulator?

They pick a capacitor (RC) or inductor (RL), set the battery voltage, the resistance, and the capacitance or inductance, and watch the charge/discharge curve sweep out in real time. A live panel shows the time constant τ, the current value on the curve, the final value it is heading toward, and whether it is charging or discharging.

Does the embed teach the time constant?

Yes. The graph marks the 63% point (charging) or 37% point (discharging) exactly at t = τ, and the readout shows τ = R·C for a capacitor or τ = L/R for an inductor computed from the values you set. Changing the resistance, capacitance or inductance updates τ live, so students can see how each component stretches or shrinks the timescale.

What iframe height should I use, especially on mobile?

The snippet ships with height="820", which is tall enough that the circuit, the component toggle, the three sliders and the readouts all fit without clipping even on a narrow phone where everything stacks into a single column. On a wider page the widget simply centres within its max-width of 560px. If you want it shorter you can lower the height, but 820 is the safe default across screen sizes.

Where can I embed it — WordPress, Wix, Squarespace, Notion?

Anywhere you can add HTML, because it is a standard iframe. In WordPress use a Custom HTML block; in Squarespace a Code/Embed block; in Wix an Embed HTML element; in Ghost an HTML card; in Notion paste the /embed/rc-circuit/ URL as an embed. On a plain HTML page or an intranet, paste the snippet straight into the markup.

Does the embedded simulator track visitors or set cookies?

No. Everything runs locally in the visitor’s browser — nothing is uploaded. The embed sets no tracking cookies and sends no analytics, so it is safe to place on a privacy-sensitive site, an intranet, or a page for students.

Widgets

How to Add an RC / RL Circuit Simulator to Your Website

LK Forge · 4 min read · Updated September 2026

You can add a full RC and RL circuit simulator to any website, blog, or classroom page with a single line of code — free, with no sign-up, no plugin, and no script to install. Visitors watch a capacitor or inductor charge and discharge along the exponential curve. This guide covers the fastest way to embed the RC & RL Circuit Simulator, what it teaches, and where it works.

The quickest way: paste one embed snippet

An embed is just an <iframe> that loads the simulator from lkforge.com, plus a small credit line. Copy this into your page’s HTML where you want the widget to appear:

<iframe src="https://lkforge.com/embed/rc-circuit/"
        width="100%" height="820" loading="lazy"
        style="border:0;max-width:560px"
        title="RC & RL Circuit Simulator by LK Forge"></iframe>
<p><a href="https://lkforge.com/tools/physics/rc-circuit/">RC & RL Circuit Simulator</a>
   by <a href="https://lkforge.com/">LK Forge</a></p>

The <iframe> is the live simulator; the <p> underneath is a plain credit link. Keep that line — the visible link is what keeps the widget free to embed. You can also copy this exact code straight from the LK Forge widget gallery.

What the widget shows

The simulator opens charging a capacitor, so a visitor sees the curve immediately and can then change it:

Capacitor / inductor toggle: switch between an RC and an RL circuit — same exponential, different component.
Battery, resistance, capacitance/inductance: three sliders that set the curve and the time constant.
Auto-cycling curve: the graph sweeps charge then discharge, marking 63% / 37% at t = τ.
Live readouts: the time constant τ, the current value, the final value and the phase.

Pick the right height

The snippet uses height="820", which fits the circuit, the toggle, the sliders and the readouts without clipping even on a narrow phone, where they stack into one column. On a wider page the widget centres within its max-width:560px. That single height works across screen sizes, so there is nothing to tweak for mobile.

Where it works

Because it is a standard iframe, the embed works anywhere you can add HTML:

WordPress: add a Custom HTML block and paste the snippet.
Squarespace: use a Code / Embed block.
Wix: add an Embed HTML / iframe element.
Ghost: insert an HTML card.
Notion: paste the /embed/rc-circuit/ URL and choose "Create embed".
Plain HTML, an intranet, or a lesson page: paste the snippet straight into the markup.

That’s the whole job. Copy the embed code from the widget gallery and paste it wherever a lesson or a blog post on capacitors, inductors, RC circuits or the time constant needs a curve students can actually watch charge up.

Grab the embed code from the LK Forge widget gallery — free, no sign-up.

Open the RC / RL Circuit Simulator

Frequently asked questions

Is embedding the RC / RL circuit simulator free?: Yes. It is free to embed on any site, with no account, no API key and no usage limits. The whole simulation runs in your visitor’s own browser, so there is no server cost — we only ask that you keep the small "RC & RL Circuit Simulator by LK Forge" credit line that comes with the embed code.
What can visitors do with the embedded simulator?: They pick a capacitor (RC) or inductor (RL), set the battery voltage, the resistance, and the capacitance or inductance, and watch the charge/discharge curve sweep out in real time. A live panel shows the time constant τ, the current value on the curve, the final value it is heading toward, and whether it is charging or discharging.
Does the embed teach the time constant?: Yes. The graph marks the 63% point (charging) or 37% point (discharging) exactly at t = τ, and the readout shows τ = R·C for a capacitor or τ = L/R for an inductor computed from the values you set. Changing the resistance, capacitance or inductance updates τ live, so students can see how each component stretches or shrinks the timescale.
What iframe height should I use, especially on mobile?: The snippet ships with height="820", which is tall enough that the circuit, the component toggle, the three sliders and the readouts all fit without clipping even on a narrow phone where everything stacks into a single column. On a wider page the widget simply centres within its max-width of 560px. If you want it shorter you can lower the height, but 820 is the safe default across screen sizes.
Where can I embed it — WordPress, Wix, Squarespace, Notion?: Anywhere you can add HTML, because it is a standard iframe. In WordPress use a Custom HTML block; in Squarespace a Code/Embed block; in Wix an Embed HTML element; in Ghost an HTML card; in Notion paste the /embed/rc-circuit/ URL as an embed. On a plain HTML page or an intranet, paste the snippet straight into the markup.
Does the embedded simulator track visitors or set cookies?: No. Everything runs locally in the visitor’s browser — nothing is uploaded. The embed sets no tracking cookies and sends no analytics, so it is safe to place on a privacy-sensitive site, an intranet, or a page for students.