When using a microwave oven, is cooking an item for two minutes at 50% the same as cooking the item for one minute at 100%?

Not at all, and for the same reason why pasta cooked for 20 minutes at 50 °C is nowhere near the same as cooking it for 10 minutes at 100 °C. Test it yourself by putting your finger in a pot of water for four minutes at 25 °C, two minutes at 50 °C, and one minute at 100 °C.

Kids at home: That was a joke. Do not actually test this yourself.

I agree it’s not the same. In my experience it will overlook the outside of the food, and not heat well through the middle. Same as cooking on the stove when the flame is too high.

In my experience some microwaves are better than others at heating at lower percentages. The one I have now seems to do 100% and then nothing in an alternating pattern to achieve 50% and I find it to be subpar compared to other microwaves I’ve had. I don’t know if it’s really doing that, but it definitely is not as good as other microwaves I’ve had.

If I don’t have a lot of time I do play with the heating directions on frozen food. If the directions are 50% I might do 60% for slightly less time. Sometimes I do 100% and halfway through I cut whatever it is in half and turn it around and do a bit more, etc.

The one I have now seems to do 100% and then nothing in an alternating pattern to achieve 50%...I don’t know if it’s really doing that

If it sounds like it is doing that, it is. On ten seconds, off tens seconds, on ten seconds, and so on.

The ones that can be dialed down to deliver a constant lower power are called inverter microwaves.

I have the on/off/on/off… type. There is a trick to get actual low power to your food, for smaller items. Put a bowl/measuring cup of water in the oven with the food, and part of the power goes to your food, part of it goes to the water.

Neat trick, you can imitate 50% without doubling the cooking time.

No. Microwaves only penetrate about 1”. After that, the heat needs to permeate the food to cook it or get it hot.

Microwaves only penetrate about 1”. After that, the heat needs to permeate the food to cook it or get it hot.

Because of this I use low power and long long cook times when I’m not in a hurry. I figure the turntable is stirring the pot for me, distributing the heat.

For heating a bowl of soup I usually go 10 minutes at 30%.

That is why some items say to keep it covered. If you have multiple items, you want a cover to keep heat from escaping certain things which take longer to heat in the middle.

By the way, I have a new way I fix “baked” potatoes in the microwave.
Instead of cutting slices in the skin, I make a cut from the end to the middle, clear through the potatoe. This way I can turn it over, and steam still has ample escape. When it is done I can finish the slice through to the other end. Two perfectly cooked open halves, steaming and ready for sour cream.