वोल्टेज डिवाइडर कैलकुलेटर — सूत्र

How to Size a Resistor for an LED

An LED needs a series resistor to limit current.

Formula

R = (V_supply - V_led) / I_led

Where:

  • V_supply = Source voltage
  • V_led = LED forward voltage drop
  • I_led = Desired LED current (commonly 20 mA)

    • Power dissipated in the resistor is P = (V_supply - V_led) x I_led.

    हल किया गया उदाहरण

    Drive a red LED (2.0 V forward) at 20 mA from a 5 V supply.

    1. Voltage across resistor = 5 - 2.0 = 3.0 V
    2. Current in amps = 20 / 1000 = 0.02 A
    3. R = 3.0 / 0.02 = 150 ohms
    4. Power = 3.0 x 0.02 = 0.06 W = 60 mW