LED and series resistor
LED and series resistor is an interactive experiment in Electronic Components, a free simulation from StudyFi Lab that runs right in your browser.
An LED is a diode that gives off light. Its forward voltage V_F is higher — about 2.0 V for red, 2.2 V for green and 3.0 V for blue — and the larger the current, the brighter it shines. The current must not exceed I_max = 20 mA or the LED burns out, so it always needs a series resistor R = (U − V_F)/I.
Try this: Set 9 V and let the calculator find the resistor for the blue LED. Then make the resistor smaller than recommended and watch what happens.
Frequently asked questions
What does the “LED and series resistor” experiment show?
An LED is a diode that gives off light. Its forward voltage V_F is higher — about 2.0 V for red, 2.2 V for green and 3.0 V for blue — and the larger the current, the brighter it shines. The current must not exceed I_max = 20 mA or the LED burns out, so it always needs a series resistor R = (U − V_F)/I.
How do I try “LED and series resistor”?
Set 9 V and let the calculator find the resistor for the blue LED. Then make the resistor smaller than recommended and watch what happens.
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