Question: what magnet are you working on, and what does it do?

Mike Dodd answered on 13 Jun 2011:

I’m working with large semi-conducting magnets. These magnets are made of hundreds of miles of very fine wire. This wire is rotated around a tube, until it forms a large ring. This ring forms the magnet, but it is not magnetic at room temperature. To make it magnetic, you need to cool it down to some of the coldest temperatures in the universe. This is done by liquid helium (the same that is in balloons, but made into a liquid), which is about 269 degrees below zero. This is very very cold, and these temperatures aren’t normally found on earth, but have to be created.

The magnets I work with are used for MRI, or Magnetic Resonance Imaging. They vary in size, depending on the strength or if it is for humans. The strength of the magnet is measured in Telsa. 1 Telsa is 1,000 times stronger than a fridge magnet. The magnet I work on is 7 Telsa! We use these magnets to image people and animals. Using MRI you can look into a person and see how their heart is beating, if they have cancer or if they have damaged their brain. It works because protons in your body, live in different environments. Protons and oxygen make up water and water can be seen very clearly on an image from MRI. Some water moves around freely, like in your blood. Whereas other water is trapped in your tissues and organs. The moving and trapped water appears different shades of grey on an image. If you have a tumour, the water is more tightly held and it appears a different colour to the tissue around it.