Use of Electromagnets in Hard Drives

Hard drives store data using electromagnets. Unlike a permanent magnet the power of an electromagnet can be adjusted with differences in the electrical current that runs through it. The hard drive has rapidly rotating stiff disks with magnetic workings that can store small binary pieces of information called bits. When the magnet is on it stores information that stays stored or magnetized even when the power is turned off. A small magnetic device called a read-write head moves back and forth over the disk to record or save data. The read-write device is moved by an activator. Platters move thousands of revolutions per minute and they can be read by read-write devices on either side. There can be multiple platters in a computer.

Junk Yard Magnet (Jack Nilsen)

Junk Yard Magnets

What are they?

Everyone has seen Junk Yard Magnets in action movies. They are usually found in the villain's lair smashing stuff. The magnets are found in Junk Yards where heavy metal, mostly from cars, needs to be moved.

How do they work?

These giant machines are essentially massive electromagnets. They work as seen in the photo below.

A coil is wrapped around a solid piece of metal. Electro current is run through the coil and this generates an electromagnetic field which in turn makes metal objects attract to one end of the electromagnet and repel from the other end.

https://www.youtube.com/watch?v=Vdkac3wJ9Aw

https://www.youtube.com/watch?v=F3mY44POVEo

ELECTROMAGNETS

             I am going to write my blog about scrapyard electromagnets. Commonly used in scrapyards, these electromagnets are super powerful, and used to lift huge amounts of metal. Commonly attached to cranes, they transport and sort metal for recycling. 

                The scrapyard crane uses electricity and magnets to charge the magnets. The magnets are supercharged by electricity and this makes them incredibly strong. The diagram below shows the how the magnets work. Please watch the video linked below to see this in action.https://www.youtube.com/watch?v=Na6-URHxOtU

Pinball Electromagnets

Some machines feature electrically operated magnets below the playfield to affect the ball's speed and/or trajectory depending upon certain conditions that are met during the game. This may be done to make the ball's movement unpredictable, to temporarily halt the ball (as a ball saver, for example), or to otherwise control the ball by non-mechanical means. The electromagnets may also be used to pick up the ball and move it to different parts of the machine. The Williams machine The Twilight Zone featured a mini-playfield that used electromagnets controlled by the flipper buttons, allowing the player to flip the ball on the mini-playfield, essentially working as invisible flippers. Contrary to somewhat popular myth, there are no professionally produced pinball machines known to contain magnets under the playfield intended to clandestinely make game play harder or increase losses, increasing gains for the machine makers.


This diagram shows one of the ways that the ball might be controlled by electromagnets during the game, making it much more unpredictable and harder to win.

Nate Battistone

5-22-19

Physics Project

Magnetic Levitation Trains

Magnetic levitation, or MagLev is a technology that uses electromagnets to lift a train off the tracks, to eliminate friction. This system has been introduced on trains in Asian countries and manny European countries. It works pretty simply, it’s like a normal train, except without wheels and an engine, it has magnets that hover above the rail enough to lift the train.

The reason that this works so well is because the reduction in friction caused by a wheel on a rail is completely avoided and replaced by a zero friction system of electro magnetics. This allows the train to both levitate off the repulsion of magnets but also propelle the train using rapidly switching magnets.

https://www.youtube.com/watch?v=m-rNILcfTKM

https://en.wikipedia.org/wiki/Maglev

Electromagnets in Garbage Disposal

          The garbage disposal was invented in 1927 by a guy named John W. Hammes, they were originally called "electric pigs" and didn't become a normal thing to have until around 50 years after they hit the market. Although the original design was much less effective and smooth as it is now, the basic principles of the garbage disposal using electromagnets is still there.
          The garbage disposal uses a high torque insulated electric motor that rotates at around 1,400-1,500 RPM, this rotation is attained by the magnetic principals of the electric motor. The electrical motor has a voltage source, a shaft, an electromagnet, and at least one additional magnet. When current from the voltage source flows through the coil, a magnetic field is produced around the electromagnet. The like fields or "poles" of the magnets repel each other (Coulomb's law)cause the motor to turn at this accelerated rate.
           The garbage disposal is used to cut up food scraps into more easily moveable and disposable pieces that can be more easily disposed of in the sewer. Although the motor in garbage disposals spins extremely fast, it is not strong enough to cut up things like spoons or knives (however it will definitely cut your finger up so please don't put your fingers in there!!)
Sources: http://www.classzone.com/vpg_ebooks/sci_sc_6/accessibility/sci_sc_6/page_540.pdf?scrlybrkr=900d5b26
https://en.wikipedia.org/wiki/Garbage_disposal_unit

Electromagnetic Field

Electromagnetic Field Detectors

Electromagnetic field detectors are the machines that ghost hunters use to detect paranormal activity. EMF detectors recognize the electromagnetic fields that are present in the area and the fluctuations of the fields. The detector is an A.C. circuit that identifies the radiation that EMF’s produce. The EMF detector picks up currents that travel back and forth super fast, like 60 times per second fast.

EMF has been a helpful tool for identifying any harmful radiation in everyday places. It's the tool to ensure that your home is safe and will not be the cause of any cancers or bad radiation.  The usage of EMF detectors has gotten very popular in the supernatural movements. Ghost Hunters believe that ghosts or spirits create an electromagnetic field around them causing to help them talk with the living.

The EMF detector has a small piece of metal that is the receiver to the electromagnetic fields. The metal then transfers a current to the LED showing you how if and how much electromagnetic disturbance there is.

Electromagnet Induction Heating

In 1831, Michael Faraday built upon the findings of Hans Christian Oersted and Andre-Marie Ampère to discover induction heating. Induction heating negates the need for an object to come into contact with a direct source of heat; instead it circulates electrical currents for increased reliability and control. Induction heating can be used to make metal malleable enough to shape, solder parts together, and create high-temperature alloys. It is highly adjustable and produces identical results when used for industrial purposes.



An induction heater requires an electromagnet, and an electronic oscillator. An electromagnet creates a magnetic field when introduced to an electric current and an electronic oscillator converts direct current to an alternating current. The alternating magnetic field generates electric currents within the conductor called eddy currents. An important fact to note is that the heat is generated inside the object and not the outside.
Induction heating is used in gaseous conductors

Generators and Electromagnetic Induction

Electromagnetic induction was first discovered in the 1830’s by Michael Faraday. Faraday noticed that when he moved a permanent magnet in and out of a coil or a single loop of wire it induced an ElectroMotive Force or emf, in other words, a Voltage, and therefore a current was produced.

So what Michael Faraday discovered was a way of producing an electrical current in a circuit by using only the force of a magnetic field and not batteries. This then lead to a very important law linking electricity with magnetism, Faraday’s Law of Electromagnetic Induction. So how does this work?.

Air-Core Hollow Coil

Electromagnetic Induction by Moving Magnet

Simple Generator Using Magnetic Induction

When the magnet shown below is moved “towards” the coil, the pointer or needle of the Galvanometer, which is basically a very sensitive center zero’ed moving-coil ammeter, will deflect away from its center position in one direction only. When the magnet stops moving and is held stationary with regards to the coil the needle of the galvanometer returns back to zero as there is no physical movement of the magnetic field.

Likewise, when the magnet is moved “away” from the coil in the other direction, the needle of the galvanometer deflects in the opposite direction with regards to the first indicating a change in polarity. Then by moving the magnet back and forth towards the coil the needle of the galvanometer will deflect left or right, positive or negative, relative to the directional motion of the magnet.

Security Systems and Electromagnetic Applications

Electromagnetic Applications in

Security and Surveillance Systems

Security and surveillance systems are used throughout business establishments and households.  Most types of systems have electromagnetic applications.  The two systems I'm going to focus on are electric circuit security systems and electronic article surveillance systems.  One is used for monitoring commercial goods and the others for intruder safety purposes. 
Electric Circuit Security Systems
ECS are used for security rather then surveillance.  These types of systems can be simple electric circuits. When the circuit is closed that means the window or door that it is on is also closed.  When the window or door is open it opens the circuit, therefore sounding the alarm.  Closing the door cuts off the flow of electricity through the circuit which then triggers an alarm. 

Electronic Article Surveillance Systems
EAS systems are used mainly for commercial purposes.  In EAS systems there is always an antenna and different electromagnetically charged tags(as seen to the left).  The antennas are constantly emitting electromagnetic energy.  On the antennas there is a transmitter and a receiver.  "The hard tags or labels themselves do not contain transmitters but an electric current is generated by the electromagnetic field of the antennas."  The tags are either activated or deactivated.  When they pass through the antenna and they are deactivated the alarm doesn't sound.  "Electric current is only generated during the short moment that the article is carried past the detection antennas and an electromagnetic interaction occurs between the antenna and the hard tag."

Electromagnetism in X-rays

Electromagnetism in X-rays

The X-ray was first discovered in Germany by scientist Wilhelm Conrad Röntgen in 1895.  He found this using a cathode ray tube in his lab. The X-ray was nearly created by accident as Rontgen found a new type of radiation the resulted in the ability to see a clear picture of the bones, fat, and tissues.  X-rays are produced by accelerating electrons.

Electromagnetism is used in X-rays as it sends electromagnetic frequency waves with high energy at the targeted area.  X-rays use electromagnetic radiation to get a clear shot of the bone. Electromagnetic radiation is a kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which electric and magnetic fields fire simultaneously.  You can see the bone in X-rays because bones absorb the x ray while the surrounding tissues don’t absorb it all.  This is why we can see such a strong contrast between the tissues in the body and the bones.  

https://www.nibib.nih.gov/science-education/science-topics/x-rays

https://www.webmd.com/a-to-z-guides/what-is-x-ray#1

This is an X-ray of my collarbone.  I broke it playing lacrosse 3 weeks ago.  You can clearly see two fractures on the left clavicle.  It typically takes 4-6 weeks for a collarbone to heal properly.  

I Ain't Afraid of no Ghosts

The EMF detector is an important tool in many ghost hunters kits. They use it to detect if there are ghosts in the room. Ghosts are said to give off electromagnetic fields (though there is no scientific evidence to it)

What Does it do? How Does it Work?

An EMF meter is an instrument for measuring electromagnetic fields. EMF meters measure A/C currents which are usually man-made. They work very similarly to a radio antenna, but with a very different detection characteristic.

What is it Used for?

In everyday life, an EMF meter is used for diagnosing problems with power lines and electrical wiring.

Electromagnetism in Door Locks

Magnetic door locks use an electromagnetic force to stop doors from opening, so they are ideal for security. Mag locks, such as the Deedlock mag locks are made up of an electromagnet and an armature plate. The plate is attached to the door, and the magnetic to the door frame.

How do  electromagnetic locks work?

Electromagnetics in Tape Recorders

Tape recorders used to be a big part of society before modern technology became relevant. The first magnetic recording device was invented in 1898 and has only escalated since then. Tape recorders use magnetic recording technology in order to record and playback audio data. These devices are not used as often today as they were in the past but some cars still require a cassette in order to play audio. As we break down a tape recorder, two main components become relevant. These are the recorder itself and the tape that is used to store the material.

Stated on the website, https://www.brighthubengineering.com/machine-design/55228-how-tape-recorders-work/

the tape itself is coated in ferric oxide powder which allows for the tape to become magnetized. The entire purpose of a tape recorder revolves around electromagnets. In order to get tape recorders to work, the tape must spin from one spool to the other. This then sends an electric current through the wire which then create a magnetic field. Here is a video which explains in depth how a magnetic tape recorder really works: https://www.youtube.com/watch?v=8o5racwCzck

While the tape recorder becomes magnetized, it has to erase all existing content on it before it is broadcasted. https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/tape-recorder tells us that while recording a sound, the magnetic domains shift around the particles which then embed a unique sound/pattern into the tape. While the sound is being played back, the magnetic fields are inducing a current. This voltage then implants itself as a magnetic signal on the tape which is then passed through a circuit in order to broadcast the true audio.

Headphones and Speakers

The loudspeaker was invented by Johann Philipp Reis in 1861 and installed in a telephone. This first invention was flawed and produced a muffled noise, and was ultimately revised by Alexander Graham Bell, who patented his invention in 1876 and then further improved by Ernest Siemens in 1877. These were a series of air compressed speakers. Then in 1898, Oliver Lodge produced the first ever moving-coil speaker. However, modern moving-coil speakers as we know them were patented by Chester W. Rice and Edward W. Kellogg in 1924. Their new model allowed the resonance of the moving system to be below the frequency where the cone's radiation impedance becomes uniform. These loudspeakers primarily used electromagnets since the larger, more powerful magnets were generally too expensive.

Early Model of Loudspeakers

Headphones were invented by Utahn engineer Nathaniel Baldwin on his kitchen table in 1910. His model, while rejected by skeptical private investors, was used by the US Navy who bought 100 pairs. Unfortunately, Baldwin lost his fortune supporting the break-off fundamentalist Mormon movement in Southern Utah. However, his invention went forward in WWII and was primarily used in the military until present day when headphones are commonly used to listen to videos and music on a computer, phone, or other portable electronic device.

First Ever Headphones

Both Loudspeakers and Headphones convert electrical signals into sound waves. The music score in question sends an alternating electric current through the cables to the drivers, which are miniature speakers located inside of the headphones. Then the signal is sent through a voice coil in the driver, which is what ultimately generates a magnetic field. The voice coil then attracts and repels the alternating current from the magnet. It moves back and forth between 20 to 20,000 times per second depending on the sound wave it is producing. Headphones are essential two miniature loudspeakers that only have to deliver the volume of air inside your ear canal.

Electromagnets in Bells and Buzzers

Around 1850 John Mirand added a clapper and gong to Johann Philipp Wagner and Christian Ernst Neeff's old design to make the standard electric bell we know today. Electric bells are made up of one or more electromagnets, made of a coil of wire wrapped around an iron core, that attracts an iron armature with a clapper. When an electric current is sent through the coils, the electromagnet creates a magnetic field which pulls the armature towards it, causing the clapper to strike the bell. They were made to operate on very low amounts of voltage (five to twenty-four volts). This specific type of mechanism can be seen in doorbells, buzzers, telephones, and fire alarms. 

( older electric doorbell )

In an interrupter bell, the bell gets hit by a spring-loaded clapper ( an arm with a metal ball at the end of it) that is actuated by an electromagnet. The clapper is held away from the bell, when at rest, but when the switch closes it allows an electric current to flow from the battery, through the electromagnet. This creates a magnetic field, that attracts the metal of the clapper to the bell, resulting in a tap. This opens the electrical contacts (depicted as 'T'), which simultaneously interrupts the current to the electromagnet, resulting in the collapse of the magnetic field. This then closes the contact again and allows the current to flow back through the electromagnet, pulling the clapper back over to the bell, making another tap. It is this cycle that then repeats many times per second to make the traditional school bell sound. A buzzer uses the same mechanics as an interrupter bell, just on a smaller and quieter scale.

( interrupter bell )

Electromagnetism in Airport Security

Airport security contains many forms of electromagnetism throughout the many different security systems. The Airport's tight security process is used to prevent harmful objects from going past a certain point, ensuring a level of security to those around, and to stop a potentially dangerous event from happening. These security devices utilize electromagnetism to ensure the safety of those traveling, prevent something truly dangerous from occurring.


In the Airport, there are many uses of electromagnetism through different security scanners. But the two most used systems are metal detectors and X-ray scanners.

Metal Detectors: are the most-used form of airport security. These devices use an electromagnetic field to detect potential harmful objects. They consist of an AC current generator and a coil. The alternating current produces a magnetic field in the coil. After the back and forth between electric and magnetic fields, an alarm is triggered and the metal object is detected. With the X-ray imagery scanner, it uses a small number of X-rays to make a 2D image if the body. These X-rays bounce off of the body to create data. This information is then enhanced to display the person and any possibly concealed objects. 

X-ray Scanners: also known as luggage scanners, X-rays pass through the bag inside, energy is absorbed differently by each thing inside the bag. These waves create a plate-like detector, blocking low-energy waves, allowing high-energy waves to hit the second plate. These two detectors are what allow TSA workers ability to examen what is inside each bag. Measuring the intensity after these waves hit the object, to determine its harmful capabilities.

MAGLEV

Magnetic Levitation

Magnetic Levitation is when an object is suspended in midair with no means other than electromagnetism. It can be used for entertainment, but is also very useful at reducing friction or counteracting gravitational forces. Magnetic levitation, or maglev, consists of two primary forces: the lifting force, keeping the object up in the air, and stability, which ensures the object does not slide out of the magnetic field. 

A levitating top, spinning on top of a magnetic field.

One example of an everyday use of maglev is maglev trains. These trains, instead of having the wheels physically on the tracks, have electromagnets in the rails as well as in the part of the train "connected" to the tracks. This eliminates the friction that would create an inefficient use of energy. When activated, the electromagnets send current in one direction, propelling the train forwards on the track, until it needs to slow down, in which case the magnets create a backwards flow of current to slow the forwards progress of the train. 

A maglev train

https://en.wikipedia.org/wiki/Magnetic_levitation

https://www.youtube.com/watch?v=SKQdJZib2vs