Resistance and ohm's law with light bulb

AI Thread Summary
The discussion focuses on calculating the diameter of a tungsten filament in a light bulb, given its resistance of 0.07 ohms and length of 27 cm. The relevant equations include Ohm's law, R = ρ(L/A), and the area of a circular cross-section, A = (πD²/4). Participants clarify that to find the diameter, one must first calculate the area using the resistivity of tungsten, which is 5.6 x 10^-8. After determining the area, the diameter can be derived using the formula d = 2*sqrt(A/π). The conversation emphasizes the importance of correctly applying these formulas to solve the problem.
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Homework Statement



the tungsten filament of a light bulb has a resistance of .07 ohm. if the filament is 27 cm long, what is the diameter



Homework Equations



R= p(L/A)

Area of a circular cross section = (PiD^2/4)

The Attempt at a Solution



R= p(L/A) A= (pL)/r

Homework Statement



resistance .07 ohm. lengh= .27m, resistivity= 5.6x10^-8
diameter ?

Homework Equations



A= (pL)/r
 
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can i get some help
 
Ok, you have the right equations. From the last equation you wrote and the values you listed, what is the area A?

Once you have that, find the diameter from d=2*sqrt(A/pi).
 

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