A 100W light bulb is joined across a 120 V potential.
a) Determine the current via the light bulb
b) Determine the resistance of the light bulb?
c) This power rating is given for a warm bulb (3000 deg C) then the light is at room temp (20 deg C), find the resistance of the tungsten filament?
d) Copper is employed as the wire leading up to the tungsten filament. Determine the drift velocity of the electrons in the copper? Copper consists of 1.10 x 1029 electrons/m3 and the wire consists ofa radius of 1.00 mm2.
- Resistivity of copper 1.7 x 10-8 ; temp coefficient of resistivity is 3.9 x 10-3
- Resistivity of tungsten 5.6 x 10-8 ; temp coefficient of resistivity is 4.5 x 10-3