No, microwaving food without covering the dish does not cause radiation leakage. Microwaves use a form of electromagnetic radiation called microwaves to heat food. These microwaves are contained within the microwave oven and do not leak out into the surrounding area when used properly.
The microwave oven is designed with a metal enclosure that prevents the microwaves from escaping. The oven door has a mesh screen that blocks the microwaves while allowing you to see inside. As long as the oven door is not damaged or has any gaps or cracks, the microwaves will remain contained within the oven during operation.
However, it's important to note that you should not use metal containers or aluminum foil in the microwave, as they can cause sparks and potentially damage the oven or create a fire hazard. When microwaving food, it's generally recommended to use microwave-safe containers, cover the dish with a microwave-safe lid or plastic wrap to prevent splattering, and follow the manufacturer's instructions for safe operation.