Microwaves can be found in almost all household kitchens. We've all used the microwave to heat our food. But have you ever wondered what is happening inside the microwave? How does the food come out cooked or hot?
How do microwaves cook food?
Microwaves cook foods using microwaves (a type of radio wave that carries electromagnetic energy), hence their name.
When you put your food into the microwave, set the timer and press start, the magnetron (microwave generator) converts the electrical energy from the electricity outlet into radio waves. These radio waves are transmitted through a wave guide. The microwaves will be reflected around inside the microwave. But when it comes in contact with the food, it gets absorbed. It doesn’t pass through the food though, because as it travels into the food it loses energy. Microwaves can only travel two centimetres or so before all its energy is absorbed by the fats, sugar and water.. When the microwaves penetrates the food it |
stimulates the particles causing them to vibrate. When particles vibrate, it generates heat which cooks the food. The food is placed on a turntable that spins, allowing the food to be cooked evenly.
If microwaves can only travel can only travel about two centimetres, how can it cook food that is thicker than two centimetres? Well, one way heat can travel is by conduction which is when the particles vibrate and ‘bumps’ into the neighbouring particles and this continues on like a domino effect. So when the outer layer of the food is heated, the heat slowly travels to the colder |
region (the centre) of the food. The time it takes to heat the food depends on the size, what is it made off or even the container that you are cooking the food in (glass of milk – glass is a poor conductor of heat). But eventually, the food will be entirely cooked or hot. The outside of the food always be hotter than the inside unless the centre has more liquid content.
For example, when you heat a meat pie, the centre of the pie has a lot more liquid than the outside crust. The microwave stimulates the particles in liquid more strongly as compared to solids. So when you cook the pie in a microwave, the outside may be barely warm while the inside could be very hot!
For example, when you heat a meat pie, the centre of the pie has a lot more liquid than the outside crust. The microwave stimulates the particles in liquid more strongly as compared to solids. So when you cook the pie in a microwave, the outside may be barely warm while the inside could be very hot!
Why does a microwave cook fast than an oven?
When we cook meat pies, the directions normally requires the pie to baked for 25 minutes in the oven but only 4 minutes in the microwave. Why does the food need to be cooked much longer in the oven?
Most ovens we have in our kitchens are convectional ovens which cooks food by heating the convection currents (air) which then transfers the heat to the food. By the sound of it, it already seems like this process will take longer. On the contrary, microwaves are designed to heat the water molecules in the food. The microwaves are directly transmitted into the food while the heat from the air is slowly being transferred into the food. Also to take into account, air is a poor conductor of heat so it will take a while before the surrounding air actually gets hot; therefore, making the oven cook the food a lot slower than a microwave. |