When or why are magnets safe to use now?
In: Technology
Older computer hard drives are magnetic, and a strong magnet can destroy the data on them.
CRT monitors also rely on magnetic fields to display an image, so a magnet can break the display.
Newer technology doesn’t work that way. SSDs and LEDs aren’t as easily affected by the kind of weak magnet that you’d use in a phone case.
Credit cards have a magnetic strip (swipe type) with their information on them. Magnets could erase this info. Nowadays, most cards have chips (insert type and/or tap type) which aren’t damaged by magnets. The magnetic strip still usually exists as a backup, and still is likely damaged by magnets. If you’re holding your card near magnets, the strip is probably erased, but you can still insert or tap with it but likely not swipe.
It’s already been touched on slightly, but the technology behind data storage has changed pretty significantly.
In a hard drive you have moving parts, to put it simply:
* A read/write head passes over a spinning disc called a platter.
* This platter is coated with a magnetised layer with sectional areas where the data is stored
* When the write head records data on areas it changes the direction of the magnetic field
* ‘0’ might be represented by the field orientating towards the head while ‘1’ has the field orientated away from it
* You end up with lots of little magnetised areas of 0s and 1s representing your data with fields pointing in different directions
Place a magnet next to them. and that direction of magnetism is going to change. Place a strong enough magnet and you can affect the moving parts themselves.
A solid state drive works by removing or giving a level of charge to a cell, think of it like the static charge you get from rubbing cloth together. This charge is unaffected by a magnet (or at least, the magnet would basically have to be powerful enough to be doing catastrophic damage to the rest of the components anyway)
Being able to store a charge in a cell rather than relying on magnetism means that modern ‘solid state’ or ‘flash’ storage is practically immune to magnetic interference.
Edit: [This](https://www.youtube.com/watch?v=5Mh3o886qpg) is a very well made video showing the basics of how modern flash storage works.
Old computers used magnetic media for storage which meant your hard drive or floppy discs could be erased if you had a magnet sitting on your computer. CRT monitors used a magnet to aim the beams for drawing the picture on the screen, so magnets would distort the image, and if left long enough would damage the picture tube.
Modern technology uses solid state storage and monitors use pixels (LCD, OLED, etc), which is dependent on an electric charge stored in a transistor, rather than the direction of a magnetic field, so weak magnets don’t affect them. You would need a magnet strong enough to induce a strong current in a computer to flip bits, one much stronger than generated by a small magnet.
Hard disk drives (HDDs) encode information with tiny magnetic fields on a disk. Those need to be changed regularly to update information. If information is changed improperly, it can cause errors and damage that information. A sufficiently strong magnet can even damage the disk enough that the needle that reads it can be pushed out of place and be unable to read data or scratch the disks.
Solid state drives (SSDs) encode information in a fundamentally different way. Basically, nothing needs to move, and there’s no magnetic fields involved, so it can’t be damaged by a magnet.
Cathode ray tube televisions (CRTs) use an electromagnet to steer a beam of electron to hit phosphors on on the screen at the right time so the right colors glow at the right time, creating an image with the right shapes and colors.
Distorting that beam distorts that image, and damaging the electromagnet or any phosphors on the screen can permanently damage the CRT’s ability to make the image.
Information is also not commonly stored on magnetic tape anymore (audio tapes, video tapes). Magnetic tape works similarly to an HDD (although it is usually analog data rather than digital) and a magnet can damage or erase that data. Tape erasers literally just drag the tape across a magnet.
The magnetic strips on credit cards aren’t designed to be rewritten, so they more easily resist a magnet’s influence
Latest Answers