Q&A for How to Preheat an Oven

It is more likely than not that your cake will not rise properly because the oven was too cold to begin with, then took too long to warm up. The cake batter needs an even temperature at the level suggested by the recipe for it to bake successfully.

You don't. Microwave ovens don't need to be preheated; they start heating your food instantly as soon as you turn it on. And you should never run a microwave oven empty.

No, it will not. An oven only has one heat option. If you set the temperature higher than necessary, you will be wasting time and money because it will have to preheat longer. Also, you may overcook your food because the temperature is too high, unless you reduce your cooking time.

Unlike using infra-red to cook the food in the case of a broil, convection uses dry, hot air to cook the food. Typically this removes moisture from the food item. Convection cooking is great for breads and cakes while using broil for meats to retain the juices through IR radiation heating.

Usually, electric ovens have coils that heat up on the stovetop rather than gas flames.

It's best to leave it closed, since the heat in the oven can escape if you open it.

Keep the door closed.

Unless the recipe states otherwise, you should bake at the same temperature.

You can buy an oven thermometer to monitor temperature. Get one and then experiment with a few different settings and mark the temperatures on your dial.

Toaster ovens are simply smaller electric ovens, the operation is largely the same.

You could. There are entire cookbooks dedicated to using a microwave for baking.

You don't need to preheat the microwave, it starts heating as soon as it turns on and doesn't need preheating.