Microwave ovens typically do not have specific temperature settings like conventional ovens. Instead, they use power levels such as low, medium, medium-high, and high to control the microwave energy output. Each power level corresponds to a percentage of the oven's maximum power.
Since microwave ovens operate differently from traditional ovens, it is not straightforward to convert a specific temperature like 350°F/175°C to a microwave power level. The cooking times and power levels in a microwave are typically determined based on trial and error and the specific food being prepared.
As for the 40 minutes mentioned, that would still depend on the power level selected and the food being cooked. Cooking times in a microwave can vary significantly based on the wattage of the microwave, the quantity and type of food, and the desired level of doneness.
To cook or reheat food properly in a microwave, it's best to follow the guidelines provided in the microwave's user manual or use specific microwave-safe recipes that provide recommended power levels and cooking times. As a general rule, start with shorter cooking times and lower power levels and adjust as needed to achieve the desired results while avoiding overcooking or uneven heating.