Resistance & LED

Question

I have calculated value of resistance using Ohms law when I am using a single LED but I am facing
problem when I am making a circuit using 2 LED but the intensity of light is a little less. What to do?

Answer ( 1 )

  1. When we calculate the value of resistance we need to consider voltage drop of the LED which varies with color of the LED.

    R= (Vbattery−Vdrop) / Curent

    Consider I am using 2 red LED’s in series V drop will be 2V+2V=4V
    V battery = 9V (if I am using 9V battery)
    Current in the series circuit at every point is same , so I=20mA
    R= (9−4)/ (20⁄1000) = 250 ohms

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