2021 Solution 02
2021 Solution 02
Isaac P Abraham
2020 Dec 25
2020 Dec 25
The resistance of a 220 V, 100 W electric bulb is measured by a multimeter to be 35 Ω. You were expecting R = V^2/W,
(220^2/100)Ω
Out[]=
484Ω
How can we explain the discrepancy?
The temperature of the bulb increases significantly when operating at 220 V compared to testing with a multimeter. The increase in temperature will increase the resistance at 220 V to match the calculated value.
Ref: Valerii Ilyushchenko (translated by V.N. Lange), "Science for everyone", Mir Publishers, Moscow, USSR.