Posted by **Alemu ** 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 -
**MathMate**, 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 -
**person 101**, 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 -
**person 101**, Friday, December 11, 2015 at 12:01pm
So 20 units of Omega

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