1. **Problem statement:** Calculate the amount of heat energy (in kJ) produced by a heating pad connected to a 220 V power supply, drawing a current of 0.27 A, and operating for 25 minutes. 2. **Formula used:** The electrical energy converted to heat is given by the formula: $$Q = U \times I \times t$$ where - $Q$ is the heat energy in joules (J), - $U$ is the voltage in volts (V), - $I$ is the current in amperes (A), - $t$ is the time in seconds (s). 3. **Important notes:** - Time must be converted from minutes to seconds because the standard unit of time in this formula is seconds. - The result in joules can be converted to kilojoules by dividing by 1000. 4. **Convert time:** $$t = 25 \text{ min} = 25 \times 60 = 1500 \text{ s}$$ 5. **Calculate heat energy:** $$Q = 220 \times 0.27 \times 1500$$ $$Q = 220 \times 405 = 89100 \text{ J}$$ 6. **Convert to kilojoules:** $$Q = \frac{89100}{1000} = 89.1 \text{ kJ}$$ **Final answer:** The heating pad produces **89.1 kJ** of heat energy when operated for 25 minutes under the given conditions.