LED Current-Limiting Resistor Lab
Three 12 V circuits light a red LED through 2.2 kΩ, 1 kΩ and 680 Ω resistors, giving about 4.8 mA, 10.4 mA and 15.3 mA. A smaller resistor raises the…
Use this circuit in class: LED and resistor lab: choose a current-limiting resistor
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The resistor sets the current: the LED keeps about 1.5 to 1.6 V across it, and the rest of the 12 V is across the resistor, so I = (12 V − V_LED) ÷ R. The smaller the resistor, the brighter the LED.
This red LED is rated for 20 mA. Work out the resistor for 20 mA, choose the next standard value up, then try a smaller one and watch the LED burn out.
What's inside
- 3× Battery
- 3× Resistor (2.2 kΩ, 1 kΩ, 680 Ω)
- 3× LED
