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**1. A standard 100 W (120 V) lightbulb contains a 8.50 cm-long tungsten filament. The high-temperature resistivity of tungsten is 9.0*10^{ - 7} ohm*m. What is the diameter of the filament?**

**2. p= resistivity, E = V/L, I = AV/pL, R = pL/A...**

**3. I know that I'm going to solve for A = pi*r**

^{2}, find r and multiply by 2 to get the diameter, but I just don't see how to do it with what I'm given. For example, I could do pi*r^{2}= IpL/V but I don't know I, or A = pL/R but I don't know R....