The heating patterns in a microwave oven can vary depending on the properties of the food or dish being heated. Here are a few factors that can contribute to some dishes getting hotter than others:
Composition: The composition of the dish or food can affect how it absorbs and retains heat. Materials such as glass, ceramic, and certain plastics are generally microwave-safe and heat up more slowly than materials like paper or certain metals. The latter can cause intense heating and even spark in the microwave.
Shape and Size: The shape and size of the dish play a role in heating patterns. Microwave ovens generate electromagnetic waves that create standing waves within the oven cavity. These waves have areas of high and low energy called "hotspots" and "cold spots." The positioning of the food or dish within these zones can impact the heating. For example, a round or cylindrical dish might distribute heat more evenly compared to a narrow, rectangular container that could have areas of uneven heating.
Water Content: Microwave ovens primarily heat food by exciting the water molecules within it. Foods with higher water content tend to heat more quickly and evenly. Moisture helps in absorbing the microwaves efficiently, while drier foods may heat less uniformly or take longer to heat.
Thickness: The thickness or depth of the food or dish can affect the heating. Microwaves penetrate food from the surface, so thicker portions may take longer to heat through than thinner ones. It's important to ensure that thicker parts of the food are thoroughly heated to prevent uneven cooking.
Placement: The placement of the dish within the microwave can impact the heating. Placing the dish closer to the center of the turntable or rotating the dish during heating can help promote more even distribution of the microwaves.
It's worth noting that microwave ovens have a turntable or rotating mechanism to help mitigate uneven heating to some extent by moving the food or dish during operation. However, variations in composition, shape, size, water content, and thickness can still lead to differences in heating patterns among different dishes in the microwave.