Calculating Resistance in a Light Bulb

[Xels]

Homework Statement

A "90-watt" light bulb uses an average power of 90W when connected to an rms voltage of 120V .

What is the resistance of the lightbulb?

Homework Equations

P_av=(V²_rms/R)

The Attempt at a Solution

90W = 120V²/R
90W/120V² = R
R = .00625$$\Omega$$

 

[gneill]

You have an algebra problem with your solving for R.

 

[Xels]

Hrmm...

P = V²/R
PR = V²
R = V²/P
R = 160$$\Omega$$

That works better huh? Thank you!