Question

the filament of 240V 100W electric lamo heats up from room temperature to its operating temperature as it heats up its resistance increases by a factor of 16 what is the resistance of this lamp at room temperature

Answer 1

The resistance will be 580 ohm 

Answer 2

p=v^2/R
100=240^2/R
R=240×240/100
R=576
factor is 16 for 1
576/16=36
R=36ohm