The electromagnetic guns in the movie are used to fight aliens, while our electromagnetic guns are used to put out fires.

There was a scene like this in the movie "Transformers 2" - an electromagnetic cannon on a US warship, after a burst of electromagnetic noise, bombarded the enemy Transformers on the top of the pyramid with huge power.

Source: Movie Stills

This scene once brought great shock to us in front of the screen, and at the same time some questions arose in our hearts. Does the electromagnetic railgun really exist? What is the difference and connection between it and the electromagnetic gun for firefighting that was successfully tested in November 2021 in my country?

1. The new favorite of the electrical age - the past and present of the electromagnetic gun

Since Faraday discovered the law of electromagnetic induction in the 19th century, people have tried to apply this scientific principle to weapons. In the early 20th century, someone proposed the hypothesis of using the Lorentz force to launch cannons. During World War II, Germany, France and other countries tried to study electromagnetic gun weapons. As a kinetic weapon, the mass and muzzle velocity of its projectile are the main parameters to measure its power. During World War II, Germany used this principle to accelerate a 10-gram projectile to a speed of 1,200 meters per second in an experiment.

In the 1970s after the war, the Australian National University was able to accelerate a 3-gram projectile to 6,000 meters per second. After decades of development, by 2010, the electromagnetic gun weapon developed by the United States was able to hit a target 200 kilometers away at five times the speed of sound, and its power was equivalent to ten times that of conventional weapons. Currently, many countries in the world, including my country, are actively researching electromagnetic guns and trying to explore their greater potential.

Photo of the US Naval Special Warfare Center testing the electromagnetic gun

Source: Wikipedia

2. The birth of electromagnetic guns: the application of energy with continuous improvement

Throughout history, every development of weapons has been accompanied by people's demand for weapons with greater power - in other words, to use energy with greater efficiency.

In primitive times, our Homo sapiens ancestors went from throwing spears with bare hands to inventing spear throwers ; later, people made bows and crossbows , using elastic deformation to quickly release stored energy; from the Middle Ages to the development of modern conventional weapons, humans used explosions, a violent chemical reaction, to invent gunpowder weapons , using large amounts of chemical energy to drive high-powered weapons in pursuit of greater lethality.

One of the two most common types of gunpowder today: black powder

Source: Wikipedia

However, using explosions to activate weapons will eventually have its limitations. First, as a violent entropy increase process, the explosion itself is violent and difficult to control. Secondly, during the explosion, a large part of the energy is released in the form of heat energy. Only a small part of the energy released by the explosion can be converted into the kinetic energy of the shell and launched. This is determined by the nature of the process itself. No matter how we improve it to increase its efficiency, it is extremely limited.

Source: Wikipedia

Therefore, finding a more efficient way to convert energy and release more energy naturally became the goal of future weapon development. As scientists searched for energy, electromagnetic guns came into their sight.

3. The principle of electromagnetic gun - a new perspective on electromagnetic induction

The current types of electromagnetic guns are mainly divided into three categories: rail guns, coil guns, and reconnection guns.

The most basic principle of this type of weapon is the Ampere force formula in our high school textbooks: F=BIL, which means that a conductor with electricity will be acted upon by a force in a magnetic field . This principle is used to accelerate a shell with a conductive shell in a fixed magnetic field and then launch it.

Railguns , also known as magnetic track guns, use the Lorentz force generated by electric current to accelerate projectiles, causing them to move along parallel rails and be fired.

Overview of the operation of the railgun Source: Wikipedia

Coil guns use one or more sets of coils. When the coils are powered on, they generate a magnetic field, which will generate attraction or repulsion on the projectiles, thereby accelerating the projectiles. Reconnection guns are a special type of coil gun, and their principles are roughly the same as those of coil guns.

Schematic diagram of the coil gun

Source: Wikipedia

Unlike traditional artillery, electromagnetic guns have a higher energy utilization efficiency. In theory, the initial velocity of an electromagnetic gun can reach 20-30 Mach. In order to achieve such a high initial velocity of the shell in a short period of time, the method of storing electric charge in a capacitor and releasing it in a short period of time is currently widely used. In this process, the energy conversion is mainly the conversion of electrical energy into kinetic energy. The energy loss will be very small, and most of the electrical energy will become part of the terrifying initial velocity of the electromagnetic shell.

In some video demonstrations, we can see that electromagnetic shells can easily penetrate multiple layers of steel plates. This is all due to its own terrifying kinetic energy. Due to its excellent energy conversion efficiency, it can achieve such power while costing much less than traditional artillery.

4. How far are the electromagnetic guns in science fiction movies from us?

In some science fiction movies, we often see electromagnetic guns. Its huge power often gives us a great shock, but in reality, what are the real uses of electromagnetic guns and how far is it from our lives?

First of all, the electromagnetic gun was first proposed as a weapon concept, and it has certain uses on the battlefield. However, in reality, the main application direction of the electromagnetic gun is not as high-end as in the movies. We carry out research on electromagnetic guns, focusing more on its cheapness and high efficiency. Compared with traditional artillery, it can achieve a higher strike speed with less cost, the interval between firings becomes shorter, and the maintenance of the gun body is more convenient. This is its essential advantage. At the same time, benefiting from its greater speed, the electromagnetic gun will be more developed in the fields of armor-piercing, anti-missile, air defense and other combat fields in the future.

In November 2021, in a video shown by CCTV, small portable electromagnetic guns such as agricultural electromagnetic guns have been put into use. They can be used for firefighting, agriculture and other aspects. These have shown that small electromagnetic guns have begun to enter the civilian field and are also gradually entering our lives.

Source: CCTV.com

So, what about the future? Humans have been looking up at the stars since ancient times, and in modern times we have begun to touch the unmanned deep space above our heads. However, since fuel and combustion aids always occupy a large part of the payload during the process of entering orbit, people's exploration of the starry sky has always been like dancing with shackles.

The electromagnetic catapult, which works on a basically the same principle as the electromagnetic gun, is developing rapidly. At present, my country has developed aircraft carriers that use electromagnetic catapults. We may be able to imagine that if this advanced technology is applied to the aerospace field in the future, our pace of exploring the starry sky will be accelerated.