The Shock of a Simple “I” That Changed the World! The Hidden Story of Electrons and Magnets Inside CRT TVs

I’m Ken Kuwako, your science trainer. Every day is an experiment.

“TVs are so thin these days, but have you ever wondered why the old ones were so bulky and heavy?”

That chunky CRT (Cathode Ray Tube) TV is a rare sight in thrift stores now. But inside that massive box lies a thrilling drama of physics that connects directly to modern cutting-edge science. Today, let’s use our “science eyes” to dissect this former star of the living room.

The Electron Gun: A Particle Accelerator in Your Home

At the heart of a CRT TV sits a device called an electron gun.

This gun fires invisible, microscopic particles called electrons at incredible speeds. These electrons hurtle toward the screen at tens of thousands of kilometers per hour. When they strike the phosphors on the screen, the impact creates light, allowing us to see an image.

You could call it a “pointillist painting made of light particles.” It’s amazing to think that every household used to have a device for manipulating microscopic particles—the kind of tech scientists use in labs—right there in the living room!

Today, I’ll share a nostalgic and exciting experiment using one of these TVs. If you happen to have an old CRT TV, try to imagine its inner workings as you read. Our theme: What happens when you bring a magnet close to a CRT TV!?

A Dance of Electrons and Magnets: The Secret Behind the Warp

What exactly happens when you bring a magnet near the screen? Watch this surprising footage.

The world on the screen warps and twists like pulled taffy! This is definitive proof that the magnetic field created by the magnet is forcibly bending the path of the electrons flying inside the TV.

When particles with an electric charge, like electrons, move through a magnetic field, they experience a special force called the Lorentz force.

This force acts in a direction perpendicular to both the electron’s motion and the magnetic field’s direction. As a result, electrons that were headed straight for the screen get shoved aside by the magnet’s power.

Normally, a CRT TV uses internal magnets (deflection coils) to control electrons with millimeter precision, scanning them across the screen at high speeds. When you bring a powerful external magnet close, that precise control is disrupted, causing the image to distort and colors to shift.

The “i” Breakthrough: A Shockwave in Japanese Science

This is a precious piece of history from the National Museum of Nature and Science, telling the story of television in Japan.

The electron gun section.

You can clearly see the ingenuity of our predecessors, who used coils to create magnetic fields and manipulate electrons at will.

TV research in Japan began in the 1920s with Professor Kenjiro Takayanagi and his team. In 1926, the very first image displayed on a CRT in the world was the Japanese katakana character “イ” (i). At a time when mechanical TVs were the norm, this method of controlling electron movement was a revolutionary invention.

Later, in 1953, NHK began broadcasting, and the TV spread across Japan as one of the “Three Sacred Treasures” (must-have appliances). The beautiful images we see on our smartphones and LCDs today exist because of this long history of perfecting technologies that bend electrons with magnets.

Are Auroras Caused by the Lorentz Force Too?

Interestingly, this phenomenon of magnets bending electrons happens on a cosmic scale. Charged particles flying from the sun are caught by Earth’s magnetic field and guided toward the North and South Poles by the Lorentz force. When they collide with the atmosphere and glow, they create the beautiful Aurora.

In other words, the same principle that powers a CRT TV is responsible for the cosmic mystery of the Aurora! Thinking about it that way makes that old TV seem a little more majestic, doesn’t it? Within the things we take for granted, there is almost always science hidden that serves as a key to decoding the world. Let’s keep cherishing our “Why?” and continue exploring the wonders of science together!

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