P = UI is used to calculate electric power! If u is not the rated voltage, can it still be used? A consumer marked with 220 V and 40 W is connected to the circuit with 110 V voltage, and the resistance remains unchanged. Why can't P = UI be used to solve this problem? Why can r = u ^ 2 / P, P = u ^ 2 / R be used only? And for example, 1000 watt hour is the small consumption of 1 kW consumer in one hour? Why does 500 W consumer consume a lot of J in one hour?

P = UI is used to calculate electric power! If u is not the rated voltage, can it still be used? A consumer marked with 220 V and 40 W is connected to the circuit with 110 V voltage, and the resistance remains unchanged. Why can't P = UI be used to solve this problem? Why can r = u ^ 2 / P, P = u ^ 2 / R be used only? And for example, 1000 watt hour is the small consumption of 1 kW consumer in one hour? Why does 500 W consumer consume a lot of J in one hour?

Can be used, as long as the actual voltage × actual current can be used, because the small bulb connected to 110V circuit can not normally light, not rated current, so can not use p = UI, but the resistance is constant, first calculate the resistance, then I = u / R calculate the current, finally use p = UI to calculate the actual power. 500W one hour consumption: 500W = 0.5KW

____ How much energy can be changed is called heat, and its symbol is____ , unit____ , abbreviated as____ The symbol of the unit is____ . heat exists only in___
Such as the title, it looks so chaotic, it seems almost the same

Heat transfer Q Joule J heat transfer process. If you have any questions, you can add questions or comments

What is the symbol of calories
Such as the title
Is kcal his symbol

Calorie

What is the international symbol for energy

The unit is Joule, J. generally, the capital e can be used to express energy, taken from energy