If you are the sort of person with a very busy life, where every minute counts, then you probably use a microwave oven quite often.

It saves time when you want to cook or warm up food, sterilise a baby’s dummy or simply make popcorn while watching your favourite TV series.

But how does a microwave oven work? Is it a health hazard or simply a means of making life easier?

These ovens make use of microwaves, electromagnetic waves produced inside the oven. These are reflected within the metal interior of the oven where they are absorbed by food. Microwaves cause water molecules (tiny particles) in food to vibrate, producing heat that cooks the food. That is why food with high water content, like fresh vegetables, can be cooked more quickly than others.

The microwave energy is changed to heat as it is absorbed by food, and does not make food radioactive or contaminated. In this respect, microwaves act just like light; when the light bulb is turned off, no light remains. Microwaves are non-ionising, which means microwave heating does not present any direct cancer risk.

Although heat is produced directly in the food, microwave ovens do not cook food from the inside out. When thick foods are cooked, the outer layers are heated and cooked primarily by microwaves, while the inside is cooked mainly by heat transfer from the hotter outer layers just like traditional ovens.

But why are metal containers not used in microwave ovens?

Any metallic materials totally reflect microwaves, causing the food to cook unevenly and possibly damage the oven itself. While materials such as glass and some plastics are mostly transparent to microwaves.

Interesting facts

• The heating effect of microwaves was discovered by accident in 1945, when Percy Spencer was standing in front of a radar and the chocolate bar in his pocket melted.

• The first food that was deliberately cooked with microwaves was popcorn. The second was an egg, which exploded in the face of one of the researchers.

• The first commercial microwave was the size of a refrigerator, weighed 340 kilos and was called ‘radar range’.

• Recent research has shown that microwaves can be used to heat up cancer cells and kill them in seconds.

Did you know…

• At birth the human body contains 270 different bones, some of which fuse together to give the 206 bones that an adult human eventually possesses.

• The fastest meteoroids travel through the solar system at a speed of around 42 kilometres per second.

• Paper was invented by the Chinese around 105AD and was kept a secret for quite a number of years.

• Our oldest radio broadcasts of the 1930s have already travelled past 100,000 stars.

For more trivia: www.um.edu.mt/think

Sound bites

• Malta suffers from much higher cases of lung cancer than would be expected, given the number of smokers on the island. Similarly, we are currently witnessing an increase in childhood respiratory illnesses. The University of Malta – through its Mobile Air Quality Laboratory, part of the Department of Geosciences – has started to map the air quality around the island. The concept is to find out what’s in the air we breathe, in particular, and determine which pollutants are causing this increase in illness to be better informed about potential risks. The mobile laboratory is focused on determining the amount of health concern pollutants such as carbon monoxide, oxides of nitrogen, volatile organic compounds, trace metals and polyaromatic hydrocarbons pose – this is both in indoor and outdoor air.

www.um.edu.mt/think/every-breath-you-take/

• SpaceX is an aerospace company that transports payloads into space commercially. It aims to reduce the astronomical costs of space transport and to make a future manned mission to Mars more feasible. It does this by using reusable launch vehicles, one of which is its nine-rocketed Falcon 9 rocket. Earlier this month this rocket successfully launched a Japanese telecommunications satellite into an extremely high-altitude orbit, which will eventually provide high-definition television to the Asia-Pacific region. It then proceeded to return to earth and land on an autonomous drone ship in the Atlantic Ocean. To top it off, this was the second time it did this within a month.

www.bbc.com/news/science-environment-36223745