physics
posted by Alemu on .
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.

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 
Use Ohmâ€™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 
So 20 units of Omega