He places a lemon between the positive and negative of the antenna of an AM radio tower and asks to turn on the transmitter: within seconds, the fruit starts to heat up and "sing," demonstrating how AM radio frequency can generate vibration and sound.

He places a lemon between the positive and negative of the antenna of an AM radio tower and asks to turn on the transmitter: within seconds, the fruit starts to heat up and “sing,” demonstrating how AM radio frequency can generate vibration and sound.

Written by Carla Teles

Published on 16/04/2026 at 12:27

Updated on 02/05/2026 at 15:47

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At the radio tower of an AM radio station, the lemon becomes a test: the radiofrequency heats, vibrates, and releases sound as soon as the transmitter is activated.

Before AM radio completely disappears with the migration, an operator decides to conduct a test that he has always mentioned to those who work near the antenna: the energy from the radio tower can generate heat and even make an object “sing”. To prove this, he chooses what seems most unlikely and precisely for that reason draws attention: a lemon.

With the transmitter off, he places the lemon in the spark gap, right between the positive and negative of the radio tower’s antenna. Then he asks them to turn on the transmitter. Within seconds, the lemon begins to heat up, sound comes out, and the fruit gets so hot that it eventually falls.

The moment when the lemon “sings” at the radio tower

Radio tower and AM radio: lemon heats up and “sings” when transmitter is turned on; radiofrequency turns into heat and sound.

The test is quite straightforward. He shows the tower, positions the lemon between the points of the antenna, and only then asks them to turn on the transmitter. The fun of the demonstration is that you can see the effect starting right away.

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Why radiofrequency heats and turns into sound

The explanation he gives is simple: amplitude modulated radiofrequency generates heat and makes the molecules vibrate. And when this vibration gains strength, it can turn into sound, as if the fruit were functioning as a body that trembles and “speaks.”

He emphasizes that the sound comes from the vibration of the molecules and the heat generated by the radiofrequency. That’s why the lemon heats up so quickly and why, at certain moments, you can hear the noise “coming out” of it.

Low or high: the water in the lemon changes what you hear

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During the demonstration, he comments that he had recorded a higher sound before, but at that moment a lower sound came out. His reading is that the lemon has a lot of water and this influences the result.

In other words, besides heating, the lemon responds like a “vibrating body,” and the amount of water can change the way the sound appears.

What this test shows about the AM radio tower

In the end, what he wants to make clear is something very straightforward: the AM radio tower radiates radio frequency with enough strength to generate heat and cause perceptible vibration. And the lemon becomes a quick way to see this without needing technical instruments.

It’s not a sophisticated trick, it’s a simple demonstration of the “look at this happening now” type.

So, being very honest: if you were there next to it and saw the lemon heat up and “sing” in seconds, would you find it curious or would you step back immediately?

He places a lemon between the positive and negative of the antenna of an AM radio tower and asks to turn on the transmitter: within seconds, the fruit starts to heat up and “sing,” demonstrating how AM radio frequency can generate vibration and sound.

At the radio tower of an AM radio station, the lemon becomes a test: the radiofrequency heats, vibrates, and releases sound as soon as the transmitter is activated.

The moment when the lemon “sings” at the radio tower

Why radiofrequency heats and turns into sound

Low or high: the water in the lemon changes what you hear

What this test shows about the AM radio tower

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He places a lemon between the positive and negative of the antenna of an AM radio tower and asks to turn on the transmitter: within seconds, the fruit starts to heat up and “sing,” demonstrating how AM radio frequency can generate vibration and sound.

At the radio tower of an AM radio station, the lemon becomes a test: the radiofrequency heats, vibrates, and releases sound as soon as the transmitter is activated.

The moment when the lemon “sings” at the radio tower

Why radiofrequency heats and turns into sound

Low or high: the water in the lemon changes what you hear

What this test shows about the AM radio tower

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Seven world powers including the US, China, and Russia are spending €22 billion on a reactor in the south of France that aims to confine plasma at 150 million degrees Celsius, ten times the temperature of the Sun’s core, using a magnetic field capable of lifting an entire aircraft carrier.

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With a wingspan of 152 meters, 76 tires, and a capacity to carry 1,270 tons, the Boeing Pelican was the giant “flying ship” that promised to cross oceans close to the water on an invisible air cushion beneath its wings.

A public school student single-handedly created a machine capable of treating water for up to 50 people using only solar energy. It was awarded third place at one of the most important science fairs in the world.

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