Final answer:
The demand factor in an electrical system is a ratio used for designing power distribution systems, considering the simultaneous use of electrical units. The energy usage of appliances like microwaves and space heaters depends on their operational time. Pressure cookers cook faster because higher pressure increases the boiling point of water.
Step-by-step explanation:
The demand factor in an electrical system is a ratio representing the percentage of total connected load that is expected to be in use simultaneously. It's a design tool to help calculate the actual electrical load to size the power distribution systems. In commercial kitchens with multiple appliances like a range, water heater, booster heater, and steam table, the demand factor ensures that the electrical system can handle the peak load without over-distribution. However, to provide the precise demand factor, specific data and table values from the National Electrical Code (NEC) or local building codes are required.
Understanding Energy Usage
When comparing two appliances like a microwave oven and a space heater, both drawing 1,500 W, the one that uses more energy is determined by its operational time. If the microwave is used for 5 minutes to heat food and the space heater runs for several hours to heat a room, the space heater will use much more energy.
Phase Changes and Pressure Cookers
Understanding phase changes is essential when considering the function of a pressure cooker. By increasing pressure inside the cooker, the boiling point of water is raised, which speeds up the cooking process. This is due to the fact that higher pressure allows steam to reach temperatures above the normal boiling point of water, resulting in faster cooking times.