Question

A certain lightbulb has a tungsten filament with a resistance of 20.3 Ω when at 20.0°C and 135 Ω when hot. Assume the resistivity of tungsten varies linearly with temperature even over the large temperature range involved here. Find the temperature of the hot filament. °C

Answer 1

Answer:

1275.61° C

Explanation:

The resistance of a conductor varies as a function of temperature and it is given as follows

$R= R_o[1+\alpha(T-T_0)]$

R_0 is the resistance at temperature T_0, R is  the resistance at T and  α is the coefficient of temperature of resistance

α= 0.0045/°C

R_0 = 20.3Ω T_0 = 20°C   and R= 135Ω  

$135= 20.3[1+0.0045(T-20)]$

T= 1275.61° C

Therefore the temperature of the hot filament =  1275.61° C