Resistance and ohm's law with light bulb

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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, represented as R = ρ(L/A), and the area of a circular cross-section, A = (πD²/4). Participants confirm the correct approach to find the area and subsequently derive the diameter using the formula D = 2*sqrt(A/π). The resistivity of tungsten is specified as 5.6 x 10^-8 ohm-meters.

PREREQUISITES
  • Understanding of Ohm's Law and resistance calculations
  • Knowledge of the resistivity of materials, specifically tungsten
  • Familiarity with geometric formulas for circular areas
  • Basic algebra for manipulating equations
NEXT STEPS
  • Calculate the area of a circular cross-section using A = (πD²/4)
  • Explore the implications of resistivity on electrical components
  • Learn about the properties of tungsten as a filament material
  • Investigate practical applications of Ohm's Law in electrical engineering
USEFUL FOR

Students studying physics or electrical engineering, educators teaching circuit theory, and anyone interested in the practical applications of resistance and material properties in electrical devices.

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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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