Calculating Voltage Difference in a Parallel and Series Circuit

[JonJon]

Homework Statement

Three 60 w 120 V bulbs are connected to a 120 V battery. 2 Bulbs are in parallel with each other in a smaller loop. The third is in series with the battery and the other loop.
find voltage difference across bulb three.

Homework Equations

R= V^2/P
1/R_loop= 1/R_1

The Attempt at a Solution

R=120^/60

1/R_total = 2/240 R_total= 120 +240 =360

I _total = V/R = 120/360

 

[Integral]

Start by finding the total circiut resistance.

You must have R_T= R_B+ R_L

Were:
R_B is the resistance of a single bulb and
R_L is the resistance of the parallel pair of bulbs.

R_L is :

$$\frac 1 {R_L} = \frac 1 {R_B} + \frac 1 {R_B}$$

So R_L = .5 R_b

Now you should be able to complete the problem on your own.

 

[JonJon]

I got V_3 is .33A * 240 = 80v but its -80v b/c its loosing right?