Did you know that the ignition button on a lighter has the same principle as the ignition switch of a gas stove, the trigger fuze of a shell, and the important device of a nuclear submarine.
Let's start with nuclear submarines.
The furthest communication distance for human beings is Voyager 1, which flew out of the solar system, which is currently 20.6 billion kilometers away from the earth (as of December 5, 2016); the furthest detection distance is those galaxies billions of light years away.
However, nuclear submarines cost more than a billion dollars. They are in the deep sea, and the distance they can "see" and the communication distance between each other are calculated in meters.
Using "short-sightedness" is far from enough to describe the short-sightedness of submarines in the sea. Compared with electromagnetic wave detection on land, submarines in the sea are truly "blind".
What many people wonder is that humans have entered the 21st century, why are underwater detection and underwater communication still so primitive and backward? Can't you use electromagnetic waves of a special frequency band? Why do we still have to use sound waves like bats?
Why use sound waves?
It is an obvious fact that in a very clear sea, the sun can reach at most 200 meters below the sea surface. Plants exist. If it is in a heavily polluted sea area, the sunlight will reach about 1 meter underwater.
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Can you recall, when swimming, how far can you see underwater?
Light is a kind of electromagnetic wave. If the penetration of light in water is so poor, then other electromagnetic waves, such as various radar waves, are not much better.
Therefore, it is a pity that although humans can use radar to detect ballistic missiles flying thousands of kilometers away, and use astronomical telescopes to observe galaxies billions of light-years away, none of these technologies work well in the sea.
So, we just say:
We know more about the surface of the moon than we know about the depths of our own planet!
We know far more about the interior of the sun than we do about the interior of the earth!
Since all kinds of radio detection cannot be used under the sea, what about other black technologies?
How about neutrinos that can penetrate the earth and use it for communication and detection? It's a pity that aliens haven't taught us yet.
What about underwater quantum communication? Maybe soon, aliens are on their way to Earth from Centaurus.
Sonar experts tell us that at present, underwater, the only thing we can rely on is sound waves, like bats!
An ordinary small bomb less than 2 kilograms explodes in water, and the sound waves can be transmitted over 4,200 kilometers. (The explosion in the moving picture is the explosion of firecrackers in the water. It can be seen that the big "balloon" formed is quickly returned to its original shape by water pressure.)
Sonar principle
When it comes to sound, we are familiar with it. The passive sonar on the submarine is equivalent to our ears, and the active sonar is a bit like the combination of the mouth and the ears. If you close your eyes and shout, you will hear the echo after two seconds, so you can say, "According to the old man's judgment, There is a big mountain at 340 meters."
Of course, active sonar in a submarine cannot rely on shouting, it relies on electricity. You said, what if there is a power outage, or the active sonar is broken, can you shout? May I?
This... there is actually a better way.
Knock on the submarine...
This method of knocking on submarines has been seen in movies. Whether it has been used in reality is untestable. We only know that countries have used grenades to explode in water to transmit information to underwater submarines.
Sound waves are the only support for nuclear submarines underwater. It is so important that we need to understand the principle of sonar. In fact, it is more interesting than we imagined.
It can be said that everyone can use the principles used in sonar, and many old smokers use it more than ten or twenty times a day, but everyone is not aware of it.
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Press down to generate an electric spark.
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piezoelectric igniter
Many people think that the black lump in the lighter is the battery, which stores electricity, but it is not. It's a piezoceramic that relies on the mechanical pressure of your thumb to create a voltage that triggers an ignition spark. This means that the igniter in the lighter does not need to be thrown away, and even if it is stored for many years, it will still work because it is not a battery.
In 1880, the brothers Pierre and Jacques Curie discovered the piezoelectric effect.
It is conceivable that the two brothers would never have imagined that their discovery would be found in the ignition switches of gas stoves in thousands of households, in the hands of smokers, in the fuzes of shells and in nuclear submarines worth more than one billion dollars in the sea. .
It is also conceivable that the public at that time did not pay much attention to the discovery of the piezoelectric effect. Scientific research has always been the same - the predecessors planted trees silently, and the descendants enjoyed the shade happily.
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Schematic diagram of the piezoelectric effect
@Tizeff
As shown in the diagram above, applying pressure to a piece of piezoelectric material creates an electric current. This is the process of converting mechanical energy into electrical energy.
There are many kinds of piezoelectric materials, one of which is piezoelectric ceramics, which is very sensitive, and a little pressure will generate a voltage. accurate.
And sound waves are pressure—sound pressure. The humming and rotating sound of the propeller of the enemy submarine generates sound pressure, and when it touches the piezoelectric ceramics of our submarine, this fluctuating sound pressure will be converted into a fluctuating voltage, so you can hear the approximate direction of the opponent's submarine up.
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Conversely, active sonar is to emit sound waves, how to emit them? It's very simple, let's take piezoelectric ceramics as an example. Since sound pressure will bring voltage, then in turn, if an electric field is applied to piezoelectric ceramics, won't piezoelectric ceramics deform? That's it, the rapid deformation of the material is the sound.
The desired frequency of sound, such as infrasound, sound waves, or ultrasonic waves, depends on the electric field we apply. This is active sonar. Of course, in addition to changing the electric field to deform the material, the magnetic field can also be used, which is the magnetostrictive effect.
submarine collision
However, although there is a sea-exploring artifact-sonar, nuclear submarines will not easily use active sonar.
That's right, if a nuclear submarine doesn't have the advantage of concealment, then it will lose a large part of its value. Although you are hiding in the deep sea, the enemy knows your location at any time. What do you want? Can't a destroyer replace you?
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You were originally a night killer, but you turned on a high-power searchlight (with active sonar) when you were walking at night. You illuminated others, the road, and yourself.
Therefore, when nuclear submarines, especially ballistic missile nuclear submarines, are submerged in the deep sea, they cannot turn on active sonar casually, and only use passive sonar to detect possible enemy ships around them.
The nuclear submarines of Britain and France collided because they did not use active sonar.
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The picture shows the British nuclear submarine Avant-Garde, which collided with the French Triumph-class nuclear submarine in 2009.
After the British and French submarines collided, the French submarine thought it had hit an unknown object and was seriously damaged. It took 3 days to return to the port. After checking the injuries, the French Navy immediately announced that it suspected it had hit a container.
When Britain heard this, it hurried to France to compare the injuries of the two submarines, and finally realized that the nuclear submarines of the two countries had collided. It's embarrassing too 😅
