1. The problem statement, all variables and given/known data A 100-W, 120-V lightbulb has a resistance of 12 ohm when cold (20°C) and 140 ohm when on (hot). Calculate its power consumption (a) at the instant it is turned on, and (b) after a few moments when it is hot. 2. Relevant equations P=IV, P=I^'R, P=V^2/R 3. The attempt at a solution Ok obvious solution is P=120^2/12 and P=120^2/140. BUT, When I calculate I(current) from first R value, I=Sqroot(P/R), it's 2,9 Amp If I want to confirm the power by multiplying that to 120V by P=IV, the figure is 351W! Why is this discrepancy ?