The voltage in typical household wiring is 120 V. A 60 W lightbulb therefore dra

Question

The voltage in typical household wiring is 120 V. A 60 W lightbulb therefore draws a current of 0.50 A when connected. Thefilament of the lightbulb has a diameter of 0.040 mm. The currentdensity in this filament is 400000000 A/m^2 in the direction of thecurrent. What is the ratio of this current density to that in a12-guage wire (diameter 0.21 cm) supplying current to the lightbulb?
Answer = _____________ (Jfilament /Jwire)
I have no clue how to do this one guys. I have posted on ithere before, but with no luck. Thanks in advance. The voltage in typical household wiring is 120 V. A 60 W lightbulb therefore draws a current of 0.50 A when connected. Thefilament of the lightbulb has a diameter of 0.040 mm. The currentdensity in this filament is 400000000 A/m^2 in the direction of thecurrent. What is the ratio of this current density to that in a12-guage wire (diameter 0.21 cm) supplying current to the lightbulb?
Answer = _____________ (Jfilament /Jwire)
I have no clue how to do this one guys. I have posted on ithere before, but with no luck. Thanks in advance.

Explanation / Answer

Current density    J = I / A = current /area Jf / Jw = Aw /Af     if both carry the samecurrent Jf / Jw = R2w / ( R2f) =.1052 / .0022 = 2760

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