What is the resistance of the spiral of an electric lamp, if during 10 min.
| September 8, 2021 | education
What is the resistance of the spiral of an electric lamp, if during 10 min. An amount of heat is released in it by an electric current of 60 kJ? Mains voltage 220V.
Initial data: t (operating time of an electric lamp) = 10 min; Q (the amount of heat released by the lamp in a given time) = 60 kJ; U (mains operating voltage) = 220 V.
SI system: t = 10 min = 10 * 60 s = 600 s; Q = 60 kJ = 60 * 10 ^ 3 J.
We calculate the resistance of the electric lamp spiral from the formula (Joule-Lenz law): Q = U ^ 2 * t / R, whence R = U ^ 2 * t / Q.
Let’s calculate: R = 220 ^ 2 * 600 / (60 * 10 ^ 3) = 484 Ohms.
Answer: The coil of an electric lamp has a resistance of 484 ohms.
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