AP Physics C E and M

Question

The filament of a light bulb has a resistance of 20.0 Ω at 20^oC and 160 Ω when the light is on. Find the temperature of the filament when the light is on. (The temperature coefficient of resistivity is 3.50x10^{-3 o}C^-1.)

Group of answer choices

939^oC

1120^oC

1440^oC

2020^oC

2310^oC

Answer 1

delta-rho/rho/temp = 3.5e-3 thus temp = delta-rho/rho /3.5e-3

delta-rho = 160-20 = 140

rho = 20

answer 2020C