In an electrical appliance, a work of 9 kJ was performed with an electric current in 15 minutes. The current in the circuit is 2 A. Determine the resistance of the device.
Task data: t (operating time of the device used) = 15 min = 900 s; A (work done by current) = 9 kJ = 9000 J; I (current in the device used) = 2 A.
We express the resistance of the device used from the formula: A = I`2 * R * t, whence R = A / (I`2 * t).
Let’s calculate: R = 9000 / (4 * 900) = 2.5 Ohm.
Answer: The resistance of the device used is 2.5 ohms.
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