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  • Ahsanul haque
    Ahsanul haque

    Member • Sep 17, 2013

    Calculating impedence.

    Hello

    I have three Led's with forward drop of 1.7 V and 10
    milliamp current. I am using 9 V battery with 15 miliamp. I used this
    website that gave me value of resistor to be used when LED in series or
    in parallel.


    For 3 led in Series, value is 390 ohms, i.e.
    9V-(1.7*3)V/0.01= 390 Ohms

    For 3 LED in 'Parallel', it states voltage drop of 243.33 Ohms ??
    Can anyone please advise me on what formula i need to use to LED in parallel to derive this value?
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  • Ahsanul haque

    Member • Sep 17, 2013

    V=IR

    Parallel:
    V = 9 - 1.7
    I = 3 * 0.01

    Series:
    V = 9 - (1.7 * 3)
    I = 0.01

    Solve for R. may be it will work.
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