August 2003
We first need to know what is going on inside of a TV picture tube. The picture tube on a TV has an electron gun in the back that constantly ’fires’ electrons at the screen. This stream of electrons is swept back and forth, and up and down across the screen many times a second. The actual speed of the electrons can be varied and the position the electron hits the back of the screen is also controlled.
The screen is coated with a material that glows when struck by an electron. In color tubes there are different tiny spots that glow red, green, or blue, with an electron gun allocated for each color. With all the spots glowing at slightly different times, places, and with varying intensities, a picture is painted on the screen. The speed and position the electrons strike are all controlled electronically. When you view a TV you do not notice the individual spots or the sweeping of the beam across the screen. Your eye simply combines all of this to give you a clear picture.
Now how does a magnet affect all of this? A magnet does not exert a force on a stationary electron. However, if the electron moves, a force suddenly appears! This force is proportional to the charge on the electron, the speed with which the electron moves, and the strength of the magnetic field. In the television tube the electrons forming or painting the picture are moving as they are shot from the back of the tube to the front. When a magnet is brought close to the picture tube, the interaction between the flying electrons and the magnetic field creates a force that throws the electrons off course. Now the electrons are hitting the screen in places they were not intended to strike and the picture becomes distorted.
Many televisions have a device called a degaussing coil that removes small magnetic fields that may form in the picture tube. Manufacturers often use what is called a degaussing coil. The word degaussing comes from the fact that the strength of magnetic fields is sometimes given in units of Gauss. This is one reason you should not place a video tape directly on top of the television. The degaussing equipment might distort some of the material stored on the magnetic tape.
The forces that magnetic fields create on moving charges are of critical importance in science. Such forces are used in cyclotrons (machines used to probe the nature of matter) and atomic mass spectrometers (devices that measure atomic masses.) This force is even responsible for trapping the solar wind particles resulting in the brilliant auroras at our polar regions.
Caution: Do not hold a magnet too close to the TV screen. It could permanently distort the screen which cannot be corrected by degaussing equipment.
FAQs
When a magnet is brought close to the picture tube, the interaction between the flying electrons and the magnetic field creates a force that throws the electrons off course. Now the electrons are hitting the screen in places they were not intended to strike and the picture becomes distorted.
Why can't you put a magnet near a TV? ›
TV and computer have magnetic materials and electronic circuits inside them which will be damaged in their working when magnets are placed near them as they interfere with these magnetic components.
Why will the magnet placed in front of a television picture tube distort the picture? ›
A magnet distorts the picture as it distorts the path of electrons flowing from the electron gun towards the screen inside the tv. As electrons are negatively charged particles, their motion is distorted by a magnet. So it is these electrons, not photons, which are distorted by the magnet.
What happens when a magnet touches a screen? ›
But if you shove a magnet on your TV screen this will interfere with the magnetic field guiding the electron and the travelling electron itself. The electron will be deflected off its intended path and not hit the correct spot on the back of the screen, distorting your image and the show you were trying to watch.
Why did television get dark patches when magnet is brought near its screen? ›
A magnet distorts the picture when the path of electrons flowing from the electron gun towards the screen inside the tv gets distorted. As electrons are negatively charged particles, their motion is distorted by a magnet. Hence, the dark patch is formed due to the distorted path of electrons on the TV screen.
Why do magnets distort TV screens? ›
When a magnet is brought close to the picture tube, the interaction between the flying electrons and the magnetic field creates a force that throws the electrons off course. Now the electrons are hitting the screen in places they were not intended to strike and the picture becomes distorted.
Is it bad to put magnets near electronics? ›
But did you know that you should keep your electronic devices away from magnets? Magnetic fields can impact your device by stripping away the device's programming and erasing stored information.
What screens are affected by magnets? ›
It's a common myth that all display devices are affected by magnets. You can hold a magnet up to most types of displays without damaging them. Only CRTs are affected by magnets, which is due to their use of a built-in magnet for controlling the electrons. LCDs, OLEDs and all other modern displays are magnet-safe.
Can the magnetic effect of the magnets pass through a screen? ›
Assertion : The magnetic effects of magnet can pass through the screens of substances such as plastic, paper, glass etc. Reason : A magnet when brought near a plastic ruler, it attracts the plastic ruler towards it.
Do magnets affect TV antennas? ›
Do magnets affect antennas? - Quora. Not usually. However, a ferrite rod antenna would be detuned by a strong permanent magnet. If the antenna is small, like in a phone, a blob of conductive or magnetic material can change its radiation pattern.
The longer a card is exposed to a magnet (usually an inch or closer), the more likely the magnet is to erase information on the magnetic strip. Thankfully, it may take multiple, long-term interactions with a magnet to cause harm to your card.
Is it safe to put a magnet on the back of a phone? ›
Therefore, your phone is generally safe around magnets.
Can you wear a magnetic bracelet next to a smart watch? ›
You should not wear your magnetic bracelet next to your Apple watch or your normal watch. We recommend you wear it on a different wrist.
What causes a TV picture to go dark? ›
It could be caused by incorrect installation, a faulty input signal, bad cable connections, poor components, or low screen brightness settings.
Why a strong magnet held near a CRT television screen causes the picture to become distorted? ›
When you hold a strong magnet too close to the screen, the magnetic field puts a force on the moving electrons F = q v B sin These errant electrons then cause parts of the screen to light up that aren't supposed to be lit and cause other parts to be slightly darker than they are supposed to be.
How does a picture appear on the TV screen? ›
The display sends light and electric current through the liquid crystal. The electric current causes the solid parts to move around. They block or let light through in a certain way to make the picture on the screen.
Should a magnet be kept near a TV or a mobile? ›
Electrical appliances such as televisions, mobiles, CDs, and computers have magnetic storage devices inside them. When we bring external magnets near these appliances, the external magnets will interfere with the magnetic components of the appliances and may damage them.
How do you demagnetize a TV? ›
Another alternative which has been known to work is to place another similar size monitor face-to-face with the suspect monitor (take care not to bump or scratch the screens!) and activate degauss function on the working monitor. While not ideal, this may be enough to also degauss the broken one.
Why should magnets be kept away from electronic items? ›
Keeping magnetic objects near electronic devices leads to demagnetisation which may erase all the important information stored in them.
