The current in a 100 watt lightbulb is 0800 A The filament

The current in a 100 watt lightbulb is 0.800 A . The filament inside the bulb is 0.260 mm in diameter. Part A What is the current density in the filament? Express your answer to three significant figures and include the appropriate units. Part B What is the electron current in the filament? Express your answer using three significant figures.

Solution

A. Current density J = I/A

J= 0.8/(3.14*0.13^2*10^-6) = 1.51*10^7 Amp/m^2

B. I = n*e

n = 0.8/(1.6*10^-19) = 5*10^18 electron current