Can magnets damage electronics?

Strong magnets can damage electronics or erase data from data carriers. However, not all types of data carriers and electronics are affected by magnets.

Summary

Magnets have no effect on:

• USB flash drives
• SD cards
• CDs, DVDs
• Cameras
• Digital cameras

Magnets can erase data on:

• payment cards
• other magnetic cards (loyalty cards, gift cards, hotel cards)
• HDD hard disks
• old videocassettes, audiocassettes

Magnets can damage:

• mobile phones, tablets (however, they cannot delete data)
• compass
• mechanical watch
• CRT and LCD monitors, televisions
• pacemakers

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Cell phones, tablets

Cell phones and tablets should continue to function properly even when exposed to strong magnets. Magnets will never erase data stored in a mobile phone or tablet.

However, magnets can damage the compass built into many mobile phones.

The magnetic field created by neodymium magnets is much stronger in their vicinity than the Earth’s magnetic field. Therefore, a cell phone placed near a magnet points north in the direction of the lines of force and not to the geographic north pole:

The problem can occur if a strong magnet magnetises the metal parts of the mobile phone and they retain some of their magnetisation even after the magnet is removed. The compass then continues to malfunction.

The built-in compass function is used by various GPS applications and Google Maps, which determine the orientation of the mobile phone thanks to the compass.

A tablet with a built-in compass can respond to a magnetic field in a similar way.

If you do not have a compass in your mobile/tablet, magnets should not affect it.

Magnetic cards

Data on all magnetic cards can be erased by approaching the magnets. However, there are two types of magnetic cards:

• HiCo– cards more resistant to magnets. These include all credit and debit cards and have a dark brown or black magnetic strip on them. A magnetic field of 400 Gauss is required to damage them.
  • Safe distance from the magnet10x10x10 mm: 17 mm
  • Safe distance from the magnet40x40x20 mm: 57 mm
• LoCo– cards less resistant to magnets. They are used in loyalty cards, gift cards with credit or hotel cards and have a pale brown magnetic strip on them. A magnetic field of 30 Gauss is required to damage them.
  • Safe distance from the magnet10x10x10 mm: 48 mm
  • Safe distance from the magnet40x40x20 mm: 150 mm

Hard drives

It is possible to remove data from a hard disk with an extremely strong magnet if you run it over the surface of the HDD. Even then, there is no guarantee that any data will be deleted. Hard drives themselves contain strong neodymium magnets. It would take a much stronger magnet to damage them.

A magnet placed on the surface of the computer cannot damage the hard disk.

If you want to erase data from a hard drive, using a magnet is not a reliable method.

Old videocassettes and audiocassettes

Data on cassettes is very easy to remove using magnets. If you need to quickly erase a record on the tape, just touch it gently with the neodymium magnet:

To prevent data loss on old cartridges, keep them at least half a metre away from smaller and a metre away from large neodymium magnets.

Mechanical watches

A strong magnetic field can magnetize metal parts of the watch such as the spiral spring. It is then attracted to other metal parts of the watch, which can slow down or speed up its oscillation.

Most of today’s watches meet the modern ISO 764 standard and are resistant to a magnetic field of 60 Gauss. With such a watch:

• Safe distance from magnet 10x10x10 mm: 28 mm
• Safe distance from the magnet40x40x20 mm: 90 mm

Other watches may be more sensitive to magnets.

If your watch has stopped working after being exposed to magnets, take it to a watch repair shop. They can be reversely demagnetised by an alternating magnetic field. You can also use your own demagnetiser for watches and small tools. They can be bought from €10.

Pacemakers

A strong magnetic field can switch the implanted pacemaker into test mode and thus temporarily affect its functioning. People with implanted pacemakers should avoid strong magnets.

USB flash drives, SD cards, CDs and DVDs, cameras, camcorders

USB flash drives, SD cards, CDs and DVDs do not use magnetic technology to store data and are not affected by magnets.

Digital cameras and camcorders also cannot be damaged by magnets.