The entire world is connected to long-distance communication, moving stealthily through the dark without being detected, and observation from far from all becomes commonplace.
But any moment you can know exactly where you are on the planet, join us now on a journey through the key moments that have allowed Humanity to master electromagnetic waves.
Sound Waves: Are They Really Longitudinal Waves?
Definition Of Sound waves:
“Sound waves are waves of energy that are created by movement. They are created by any object that moves across any medium. When an object moves across a medium, it creates a disturbance which moves out in all directions. This is called a wave. Sound waves are created in the same way”.
Let’s Understand This with an example
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Suppose you speak into one of the pops. The sound of your voice passes through to the other side that works so well. So how does it work when we speak? Does our larynx emit vibrations?
These are called sound waves.
“Sound waves are longitudinal waves. In a longitudinal wave, the particles of the medium are pushed one way and then the other. The medium’s particles oscillate back and forth as a result of these pushes. This movement creates an interference pattern that propagates through a medium. A longitudinal wave propagates across a medium in a direction perpendicular to the direction of the wave.”
How it is work?
- The vibrations propagate through the air and to the bottom of the pot and are then carried along the string 3 meters away.
- The bottom of the second pot starts to vibrate in turn, and the waves then travel through the air to the listener’s Eardrum.
- The principal limit is the length of the string. If it is too long, the sound wave will no longer have enough energy when it reaches the end.
The telegraph works in a slightly different way. The principle is not based on a sound wave but an electric current.
Here’s a simplified version.
All you need is some electric wire, a battery, and a light bulb. Suppose my circuit is open, IE.
If the current doesn’t flow, the bulb is off. If I close the course, the bulb lights up, and you don’t need more than that to communicate fundamentally.
You need to define a code.
For example, the light bulb on means yes, and off means no. The more sophisticated the code is, like Morse code, the more complex the messages can be.
The significant advantage over yogurt pots is that we can send the message much further and faster.
The electric telegraph was invented In 1832, coupled with the American Samuel Morse Mark’s code, a turning point.
Its speed range is unrivaled in just ten years 35000 kilometers of lines were already in service in the United States.
Mechanical Waves Def
What exactly is a wave to keep it simple? We can say that a wave is the movement of a disturbance. Okay, that isn’t much help.
Mechanical waves are also called waves of energy. They are often observed in action in the form of waves crashing on the shore, waves of light, sound waves, radio waves, and so on. Mechanical waves are waves of energy that are observed in the form of waves crashing on the shore, waves of light, sound waves, radio waves, and so on.
So to be more concrete, let’s look at this plastic tub filled with water for the moment. Everything is calm on the surface. But if I drop a stone into it, you have a perfect wave.
The surface is set in motion by a concentric movement that repeats as it moves away from the point of impact. The surface dips down once the wave has passed until another wave comes along. That is, our disturbance is a wave.
In this case, it is a mechanical wave, which means it needs a medium to propagate. This one is in liquid, but it can also be in gas-like air or solids like the string between our yogurt pop ocean waves, just like earthquakes are mechanical waves to visualize them better.
Let’s do what Galileo did and shake these two ropes at different speeds. The shakes travel along the ropes, making them move up and down.
Amplitude, wavelength and frequency
It is said that the more oscillations there are per second, the higher the frequency of a wave.
A frequency is measured in hertz 100 Hertz indicates 100 oscillations per second. Now let’s press pause. The two ropes are not the same shape.
One has relatively close, short oscillations. The other has a single long variation. The intensity of the variations is called amplitude.
The greater the amplitude of a sound wave. The louder, the sound stays with us. Wavelength is used to describe the length of each oscillation.
Wavelength and frequency are related. And finally, velocity equates to the speed at which the wave moves through the medium.
Double slit experiment
The end of the 17th century was marked by a significant scientific conflict concerning a fundamental question. What is light? Is it made up of tiny particles, as described in theory, defended by Isaac Newton? Or is it composed of waves, as Christian Huygens’s things?
There will not settle this question in their life much later than the dawn of the 19th century. An Englishman, Thomas Young, experimented with making him a celebrity, the famous double-slit experiment.
Double slit experiment at home
It takes two different steps to understand it properly. First, you need a sheet of cardboard, a smooth plaster wall, and a can of spray paint; cut a slit in the cardboard and use it as a stencil to paint the wall.
Okay, so no big surprises. So far, you get a patch of paint roughly the shape of the slit. Now cut a second slit and do it again. You get two parallel paint marks. We could compare this first part of the experiment to Newton’s Theory.
Light is made up of tiny particles, just as the paint is made of droplets. And when they both move, they do so in a straight line. Keep this result in mind and move on to step two, observing waves that impact the surface of the water in our plastic tub. This is what our waves look like when they move smoothly across the surface unobstructed.
Now, here is the same experiment. But this time, there’s a barrier with a slit in the middle, the plastic tub, the waves change shape and become circular. They are said to be diffracted with two slits. It becomes fascinating in certain areas. The two waves seem to add together and increase in size in others.
Conversely, they seem to cancel each other out. The waves have disappeared. This is called interference; young tried the same thing with light. And you know what? He got the same results as with the plastic tub.
The patches of light on the wall are typical of a wave. So if we only did this one experiment, a light would be a wave and not a particle, as humans had predicted.
Light is made Up of Tiny Particles Called Photons
Electromagnetic waves frequency
Maxwell Equation For Electromagnetism
Scotland, 19th century James Clerk Maxwell is working to unify to Great fields of science. Electricity and magnetism are equations known as Maxwell’s equations are still widely used today and laid the foundations of modern physics. He also observed that certain electrical and magnetic phenomena could create a particular wave type. Today, they are called electromagnetic waves in 1889 while validating Maxwell’s equations.
The German physicist Heinrich Hertz observed that it could generate electric arcs short distances without any contact. He proves that they are produced by electromagnetic waves whose speed he manages to measure nearly 300000 kilometers.
At the same time, the speed of light is finally measured, and the results coincide. This is another clue. Light appears to be an electromagnetic wave.
There are a lot of electromagnetic waves, a truly vast number. Look at this family portrait. They are all listed. It’s called the electromagnetic spectrum.
We have to be careful not to mix them up. We can sort them by wavelength in our chart, the longest wavelength. And therefore, the lowest frequencies are on the left.
The very high frequency is on the right. So, from left to right.
First, we have radiotelephone and television waves, then come to the microwaves used by Wi-Fi and radar and for heating our meals.
The wavelengths keep getting shorter and shorter and become infrared waves beneficial for remote controls, night vision, goggles, and laser cutting.
Then we come to a concise but critical section, visible light.
Thanks to this tiny slice of the electromagnetic spectrum, we can see the world around us. Suppose we continue our exploration into the world of high frequencies.
In that case, we will successively meet ultraviolet rays like those emitted by the sun, then x-rays used in medical Radiology Imaging. And finally, gamma rays, which are notably used for destroying cancer cells,
1890 the Catholic, The French physicist Edward Morley, manages to reproduce an experiment done by an Italian colleague. When an electric current flows through iron filings, he finds that they tend to group.
Barney observed the same phenomenon occurring near an electric generator. He realizes that it is possible to pick up an electromagnetic wave at a distance without physical contact. He calls his detection device The radio conductor.
A few years later, Alexander pop, off of physics teacher at the Russian naval School, improved the machine by adding a long metal rod, and the radio antenna was born.
Generation of Electromagnetic field Using Magnet and Electric Coil
So to create a mechanical way, you need to drop a stone into a pond. But how do you generate an electromagnetic wave? We need some equipment. Let’s start with these magnets.
If we bring them together, they attract or repel each other. Why? Because each of them has a magnetic field that is invisible to the naked eye.
This field acts as a force of attraction or repulsion.
Now, if I pass my magnet through a copper coil connected to a voltmeter, wow, the needle moves. As it progresses, the magnetic field of the interest generates an electric current at a distance without even touching the coil.
We say that the magnet induces an electric current And the great thing is that the opposite also works. The two fields are linked. The variation in an electric field generated a magnetic field and vice versa.
How Antenna Works?
Now that we know this, let’s pass an alternating electric current that moves in One Direction. And then in the other, through a conducting metal bar, an antenna, the alternating movement of the current will disturb the electromagnetic field. This disturbance is our electromagnetic wave.
If we place another antenna a short distance away, the emitted waves will travel to it through the air, and in turn, induce an electric current in the middle. Thanks to a lock, we have just transmitted an electric signal over a distance. It doesn’t need a physical medium to carry it. An electromagnetic wave travels much faster and further than a mechanical wave, such as a sound.
Working Of Radio
At the end of the 19th century, after the invention of the radio conductor and the antenna, many other scientists and inventors would file patents allowing the development of the radio on Christmas Eve. In 1906. The Canadian Reginald Fessenden made the first-ever successful radio transmission. He spoke, sang, and played the violin in front of a microphone inserted between an
Alternating current generator and the antenna out at Sea in the middle of the dark expanse of the Atlantic. Several or struck radio-telegraph operators suddenly heard music.
How Radio Works ?
The radio is innocuous, yet few people can’t explain it correctly. How does it work? And we will soon be joining them. The function of a radio is to transmit a message from a transmitter to one or more receiving in separate distant locations with nothing connecting them. This happens when the sender of the message speaks, and he produces sound waves.
- These waves vibrate a membrane, for example, in a microphone and are converted into an electrical signal. This is the message but transmitted directly. It would have a shallow range and be very difficult to pick up and distorted by interference.
- All we have to do is combine it with a carrier wave, which will act as a transporter for the message. We then say that the signal is modulated. A transporter can then send the electrical Signals to an antenna, which is transmitted into the air in electromagnetic waves.
- It then travels at the speed of light until it interacts with the electric field of the receiving antenna.
- If the receiver knows the wavelength of the carrier wave, it can focus on just that frequency and analyzes variations converted back to an electrical signal. The message transits through a demodulator, which extracts the message signal from the carrier signal. It is then amplified and sent to the membrane of a loudspeaker to be finally transformed back into a sound wave.
- The message is delivered, and the whole process happens in the blink of an eye. If everyone uses the same wavelength, the messages will be superimposed and cause interference. And anyone with a receiver within range Of the transmitter can pick up and listen in on the message, even if it is not intended for them, radio waves are not very secure.
Hedy lamarr torpedo invention
Hollywood 1940 Hedy Lamarr, an Austrian actress Exile in the United States, has just been nicknamed the most beautiful woman in the world by a successful theater director. However, the expression stuck to her for a long time. Today, she is more often referred to as the actress who invented Wi-Fi. Why brilliant intellectual and great chess player? Her first marriage was to a weapons manufacturer. Hedy Lamarr soon became familiar with torpedo remote control systems in 1941, and she decided to team up with a friend and take part in the war effort against the Nazis in her way.
How Torpedo Work Using Electromagnetic Waves?
We now know how a radio works. And we know about its weak point when a radio-guided torpedo is heading towards its Target.
If we find its transmission frequency, we can divert it and neutralize it. Of course, at the frequency of the carrier, the wave is not precisely known.
The radio operator targeted by the torpedo will have to use trial and error. This is called frequency scanning. But sooner or later, he will come across the right one to make the task more difficult. We can use the system devised by Hedy Lamarr’s frequency-hopping spread spectrum.
The torpedo will reach its Target almost every time. That’s what frequency hopping is all about, alternating between several carrier waves spread over a wide frequency band, making the message is very difficult to jam or pickup.
Global Positioning System
In the end, Hedy Lamarr’s invention was not used during the Second World War. Art in the decades that followed was a source of inspiration for many Engineers, enabling them to make telecommunications more stable and efficient.
Take GPS. For example, in the past, Sailors navigated using the position of the Stars. They watched anxiously for the glow of the Lighthouse of Alexandria to appear today. No one would consider seeing without a satellite positioning system such as GPS, initially designed by and for the American Army in the 1970s.
This satellite positioning system is now part of our everyday lives today. It has several competitors, including the European system called Galilea.
In the family of everyday objects that everyone uses, I would like the GPS on our phones without really understanding how they work after the radio. And in our cars, the global satellite positioning system has become available everywhere. It’s super simple to use, but it is still a significant concentration of science to understand how it works.
Is GPS Using Electromagnetic Wave?
We have seen electromagnetic waves travel at the same speed as light, around 300000 kilometers per second. So a signal sent from a satellite thousands of kilometers away will arrive very quickly, but not instantaneously. It will take a few microseconds if we can precisely measure this delay using atomic clocks,
If only the effects of gravity and the super high-speed of the satellites did not adversely impact the calculations. We also need to consider Einstein’s theory of general relativity to fine-tune the calculations and prevent Francis from being wronged by several kilometers. And that is a lot of science.
Technology-based on electromagnetic waves has changed the world in this hyper-connected world. It has become easier to access the internet than to drinking water or toilets. We can be everywhere all the time. See everything, know everything, say everything. Electromagnetic waves travel through space at 300 kilometers per second at this speed. The notion of distance and time becomes, for example, that the closest planetary system to us, Alpha Centauri, with today’s technology, is located a little over four light-years away. It would take us around 100000 years to get there physically, but it would only take four years for an electromagnetic wave to reach. It makes you think.