At a voltage of 120 V, 900 J of energy was released in the heating device in 0.5 min.

univerkov | September 2, 2021 | education

At a voltage of 120 V, 900 J of energy was released in the heating device in 0.5 min. Determine what the current in the device is equal to and what is its power.

Initial data: U (effective voltage on the heating device) = 120 V; t (duration of the device) = 0.5 min (30 s); Q (released amount of heat) = 900 J.

1) The current in the device (Joule-Lenz law): Q = U * I * t, whence I = Q / (U * t) = 900 / (120 * 30) = 0.25 A.

2) Device power: P = U * I = Q / t = 120 * 0.25 = 900/30 = 30 W.

Answer: The current in the device is 0.25 A, the power of the device is 30 W.

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