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Posted by on Monday, January 4, 2010 at 8:33pm.

A string of 8 christmas tree lights connected in series to a 120v source draws a current of 0.75A.can any one show me how to find the resistance of each lights and potential differnces.

  • physics - , Monday, January 4, 2010 at 8:49pm

    Use V=IR

    Since the lights are in series, the potential drop at each light is equal, and can be calculated by 120V/8=15V.
    The current, I=0.75 is identical for all the christmas lights connected in series.

    Applying V=IR for each light, we get
    15=0.75R
    R=20Ω

  • physics - , Friday, December 11, 2015 at 11:59am

    Use Ohm’s Law

    If you read the lesson, you should know the equation for this:

    R = V/A

    where R is resistance, V is voltage, and A is amperes, so:

    R = 120/0.75 = 160.

    Since it is a series circuit, each of the bulbs should experience an equal amount of voltage and current. Thus, the same amount of resistance. Divide 160 by 8:

    160/8 = 20

  • physics - , Friday, December 11, 2015 at 12:01pm

    So 20 units of Omega

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