When heating multiple items in a microwave, you typically need to heat them for a longer time compared to heating a single item. This is because microwaves work by emitting electromagnetic waves that excite water molecules and other polar molecules in the food, causing them to vibrate and generate heat.
When you have more items in the microwave, there are more molecules that need to be heated. Each item absorbs some of the microwave energy, and as a result, the energy is distributed among all the items. This can lead to a slower and less efficient heating process for each individual item compared to when there's just one item in the microwave.
Additionally, having multiple items in the microwave can create more barriers for the microwaves to penetrate through the food. The microwaves may be blocked or absorbed by one item before reaching another, further slowing down the overall heating process.
To ensure even heating, it's important to arrange the items in the microwave so that they are evenly spaced and not stacked on top of each other. Stirring or turning the items during the heating process can also help distribute the heat more evenly.
The required heating time can vary depending on the type and quantity of items you are heating, as well as the wattage of your microwave. It's always best to follow the recommended cooking guidelines or adjust the cooking time based on your observations to achieve the desired results.