This fascinating video shows just how powerful the magnets that are used in MRI scanners really are.

And it goes a long way to explaining why medical professionals insist metal objects are kept well away from the Magnetic Resonance Imaging machine.

A group of scientists uploaded a video to YouTube where they demonstrated the true force of the magnetic field of a scanner that was about to be decommissioned.

The scientists strap up the chair before connecting it to the weight gauge for their special experiment

The object is gradually dragged closer and closer towards the MRI scanner as the tension increases

As the weight gauge hits 1,700lbs, the back of the chair's headrest flies off, to gasps from those watching

First up to feel the wrath of the magnets' power was a steel shackle. After being thrown into the scanner that was in operation, the object rattles around violently before it sticks firmly to the top.

Next up is a stapler, which we are told 'disintegrates' after being thrown into the MRI machine, believed to have been stationed in California, U.S.

A wrench is then placed inside the scanner, attached to a weight gauge. As the magnetic field kicks in the wrench bobs up and down before slamming to the bottom of the machine.

The reading on the gauge, we are told, says that the wrench is being impacted by 500lbs of tensile force.

At one point during the experiment, the force was measured at 1,200lbs, but that only increased

The stapler was said to have 'disintegrated' after it was thrown into the magnetic field

The stapler is rattled and crashed around after one of the scientists launched it into the MRI machine

BUT ARE THE MAGNETS DANGEROUS TO THE HUMAN BODY? Extensive research has been carried out into whether the magnetic fields and radio waves used during MRI scans could pose a risk to the human body. No evidence has been found to suggest there's a risk, which means MRI scans are one of the safest medical procedures currently available. Advertisement

Not content with demonstrating this level of power, the group ramp things up and swap the wrench for a chair.

Once again the chair is connected to the gauge, and you can quite clearly see it being sucked in towards the scanner.

At 700lbs of force, the chair now enters the scanner. Then the force reading ticks past 1,300lbs and at 1,700lbs a loud crash sees the back of the headrest fly off.

The video ends with one of the scientists showing the reading having reached 2,000lbs, in their words, 'about the same (weight) as a small car.

'That's why we don't have chairs with wheels in the MRI,' it concludes.

The force exerted on the wrench was recorded, just as it crashed down to be joined to the scanner

MRI scanners use powerful magnetic fields to manipulate protons in the water molecules which make up much of the human body.

Radio-frequency waves are then directed at the patient to determine the position of the protons and how they have 'lined up' under the magnetic field, building up a detailed picture of different types of tissue in the body.

The magnetic fields needed are so strong that MRI scanners always bear explicit warnings that they should not be kept near any metal objects, even paperclips.

MRI scanners tend to have a magnetic strength of between 1.5 and 3 Tesla - compared to just 0.005 Tesla for a fridge magnet.