# Magnetic Disks

Length: 1175 words (3.4 double-spaced pages)

Rating: Excellent

#### Essay Preview

Magnetic Disks
(Hard Disk)

The topic of magnetic disks is one that involves many physics related phenomenon. The intricate structure and design of “Magnetic Disks” (or hard disks) in computers include the principles of Fluid Flow, Rotational Motion, Electromagnetism, and more. This paper will focus mainly on the previously listed physics occurrences, and the design that goes into engineering the magnetic disk to include them. These physics principles are utilized in such a way that makes the hard disk a very common and useful tool, in this day and age. To most people, the magnetic disk is the most important, yet most mysterious, part of a computer system. A hard disk is a seal unit that holds computer data in the form of magnetic patterns.
Before understanding the physics principles, one must understand the physical design that induces them. A magnetic disk is a flat, circular, rigid sheet of aluminum coated with a layer of magnetic material (can be double sided). The material usually is a form of iron oxide with various other elements added. The disk rotates upon a central axis and a movable read/write head writes information along concentric tracks (circular paths traced out by motion of the disk) on it. Multiple disks can be stacked to store more information. Typically (1985) 11 disks with 22 surfaces, of which 20 are used (minus top/bottom), are manipulated to read/write data.
The “head”, or device used to transmit data onto the magnetic disks, is an important part of the hard disk and composes most of the physics happenings. Current is passed through the head or in the physic’s case, the conductor, to produce a magnetic field around the conductor. This magnetic field then can influence the disk’s magnetic material. The head is driven by an electric motor, using electromagnetism, to exert pushing and pulling forces on magnets to the rotating shaft. In some cases the head moves to a required area on the disk, and the motion of the magnetized surface induces tiny voltage. This voltage is concentrated in the coil of the read head, and can be interpreted as the data stored on the magnetic disk. When the direction of the flow of electric current is reversed, the magnetic field’s polarity is reversed.
The head is mounted in a “slipper” (or holder) positioned above the disk at 0.5-2.5 microns from the surface. When the disk is revolving around its axis, an air current creates a velocity gradient with the surface and air.

MLA Citation:
"Magnetic Disks." 123HelpMe.com. 05 Dec 2019
<https://www.123helpme.com/view.asp?id=75790>.

## Need Writing Help?

Get feedback on grammar, clarity, concision and logic instantly.

## Efficiency of Angular Momentum Transport Essay

- ... For example, \cite{girart06} detected hour-glass shaped geometry of the magnetic field in the low-mass protostellar system NGC 1333 IRAS 4A using the Submillimeter Array polarimetry observations at 877 $\mu$m dust continuum emission. \cite{chapman13} detected a correlation between core magnetic field direction and protostellar disk symmetry axis in a few low-mass protostellar cores using the SHARP polarimeter at Caltech Submillimeter Observatory at 350 $\mu$m dust continuum emission. \cite{donati05} probably detected magnetic field with azimuthal component of order of 1 kGs in the FU Orionis accretion disk....   [tags: strength, magnetic, disks]

Research Papers
1244 words (3.6 pages)

## Computer Storage: Are memory sticks and disks likely to be obsolete by 2015?

- In the first quarter of 2012, a German business software firm (SAP) recorded a 10 per cent increase in profits from the previous year of £478 million from cloud, a method of computer storage (SAP sounds upbeat note as profits continue to rise, 2012). It is clear that methods of storing data on computers have developed rapidly in the past 60 years, from the earliest type of data storage on cylinders to data storage in cloud. The purpose of this essay is to describe this development and show that individual physical memory such as memory sticks and disks are rapidly becoming a thing of the past....   [tags: Information Technology ]

Research Papers
1848 words (5.3 pages)

## How Magnets Affect Computer Disks Essay

- How Magnets Affect Computer Disks BackGround One of the most commonly used Computer data storaged mediums is a Computer Disk or a Floppy. These are used in everyday life, in either our workplace or at home. These disks have many purposes, such as: Storing data: Floppies can be used to store software/data for short preiods of time, Transferring data: Floppies are used to transfer/copy data from one computer to another. Hiding data: Floppies are also sometimes used to hide sensitive or confidential data, because of the disk's small size it can be hidden very easily....   [tags: essays research papers]

Free Essays
1191 words (3.4 pages)

## Retrieving Data with Storage Devices Essay examples

- Storage Devices Storage devices are used to record or retrieve data in technological devices. A device that only records information is called a recording medium; it does not allow for processing of the information. They allow for ease of access for the user to retrieve any data from the device that had been previously stored. They help run programs, view page content, and even allow for interaction on some web pages. There are two types of storage in computers; a primary storage, like RAM, or Random Access Memory, and a secondary storage, like a hard drive....   [tags: computer, program, magnetic disk]

Research Papers
658 words (1.9 pages)

## Essay about Physics Of The Prototype Motor

- A total of six various motors were directly derived from the prototype motor through displacement of outer hysteresis disks and turning off/changing polarity of supply of one of the stators. These motors are depicted in Fig. 34. Fig. 34(a) displays a circumferential flux single stator-single rotor motor named M1. When the prototype motor is supplied only by one of the stators and the two external disks are away from the stators, the outcome is motor M1. It should be noted that the only hysteresis disk of this motor is the middle disk with a thickness twice as large as that of external disks....   [tags: Electric motor, Magnetic field, Permeability]

Research Papers
837 words (2.4 pages)

## Essay on The Effects Of Magnetic Permeability On The Magnetic Field

- Aeromagnetic Data Theory Scalar aeromagnetic data reflect both induced and remanent magnetic fields. Induced magnetism is caused by the earth’s magnetic field and is mainly the result of the magnetic susceptibility of the rock. Magnetic susceptibility is expressed as a unit-less proportionality constant denoted by an International System of Units (SI), which simply reflects the susceptibility of a rock to become magnetized in the presence of a magnetic field. This susceptibility is mainly a function of the rock’s magnetite content....   [tags: Magnetic field, Magnetism, Igneous rock]

Research Papers
1757 words (5 pages)

## Essay on The Effects Of Magnetic Permeability On The Magnetic Field

- Aeromagnetic Data Theory Scalar aeromagnetic data reflect both induced and remnant magnetic fields. Induced magnetism is caused by the earth’s magnetic field and is mainly the result of the magnetic susceptibility of the rock. Magnetic susceptibility is expressed as a unit-less proportionality constant denoted by an International System of Units (SI), which simply reflects the susceptibility of a rock to become magnetized in the presence of a magnetic field. This susceptibility is mainly a function of the rock’s magnetite content....   [tags: Magnetic field, Magnetism, Igneous rock, Basalt]

Research Papers
1544 words (4.4 pages)

## The Magnetic Fields Of The Magnet Essay

- Introduction: Magnetism was not studied or utilized before 1821 as it is today. A few hundred years ago people understood how magnets worked, but didn’t have many applications of the magnet because they were limited by the technology of their time. The applications of magnets today have opened a new door as to how we can harness the power of a magnet. I had a basic working knowledge of how magnets worked, such as polarity, but with researching different aspects of the magnet I have learned that we need to advance the potential capabilities of the magnet and fully understand how we can harness the magnet....   [tags: Magnetic field, Electromagnetism, Magnetism]

Research Papers
1704 words (4.9 pages)

## Interstellar Magnetic Fields And Gases Essay example

- Interstellar Magnetic Fields and Gases Interstellar magnetic fields play an important role in our galaxy by returning stellar material back out into interstellar space. The magnetic fields are frozen in place within the hot ionized gases of the interstellar medium acting as an additional energy reservoir; the magnetic fields wear several hats regarding the work that needs to be done in our galaxy. However, there is still little known about the all of the roles the ISMF plays. There is a division between large and small scale fields; the former found on the scales of the spiral arms of our galaxy, and the latter found within the interstellar space....   [tags: Magnetic field, Magnetism, Electromagnetism]

Research Papers
1687 words (4.8 pages)

## The Earth Magnetic Field Essay

- It’s the magnetic field that extends from the earth’s interior to where it meets the solaria stream of charged particles emanating from the sun. The magnetic field resembles the field of a large bar magnet near its center or that due to a uniformly magnetized sphere. Its origin is thought to be generated deep down in the earth’s core. At the surface of the earth, the pole of this equivalent bar magnet, nearest the north geographical pole is actually a south” magnetic pole. This paradoxical situation exists since by convention a north seeking end of a compass needle is defined as pointing north yet must point to a pole of opposite sense or South Pole of the earth’s magnetic field....   [tags: solaria stream, magnetic storms]

Research Papers
1754 words (5 pages)

### Popular Essays

This creates enough lift to oppose the spring pressing the head towards the disk. If there were contact with the disk, it would wear out quickly considering the disk rotates at 100km/hr. This is enough space for the magnetic field to affect the disk and read/write data. The fluid flow of the air forms a pattern typical of laminar flow, in which adjacent layers of fluid slide smoothly past each other and the flow is steady. The air under the head (shaped like an aerofoil) increases in pressure in this region. An upward force is created on the underside that is greater than the downward force on the top of the head. There is a net upward force, or lift. The greatest contribution to this lift is the reduced pressure on the upper head surface.
In order to create the appropriate voltage from the magnetized surface, we must achieve a certain rotational kinetic energy (K). By taking the calculated moment of inertia (I), of I = ½MR2 (M = mass in kg, R = radius (minus area covered by axis) in meters) and applying it to the equation, “K = ½WI2” (W = angular speed in rad/sec) we can determine its kinetic energy. Vise versa, we can use the desired kinetic energy to ascertain how fast we need the angular speed to be. A typical disk rotates at 2400 rpm, or using the conversion as follows: w = 2400 rpm = ( 2400 rev/min )( 2ð rad / 1 rev )( 1 min / 60 s ), or at 251 rad/s.
Nearly all hard disks in personal computer systems operate on magnetic principles. Purely optical drives often are used as a secondary form of storage, but the computer to which they are connected is likely to use a magnetic storage medium for primary disk storage. Due to the high performance and density capabilities of magnetic storage, optical hard disks and media probably never will totally replace magnetic storage in PC systems.
When a magnetic field is generated in the head, the field jumps the gaps of the read/write head. The field bends it as the path of least resistance to the other side of the gap, because magnetic field passes through a conductor much more easily than through air. As the field passes through the media directly under the gap, it polarizes the magnetic particles through which it passes so that they are aligned with the field. The electric force on a charged body is exerted by the electric field created by other charged bodies. The field’s polarity and, therefore, the polarity of the magnetic media are based on the direction of the flow of electric current through the coils.
The polarities of the magnetic fields of the individual magnetic particles on an erased disk normally are in a state of random disarray. Because the fields of the individual particles point in random directions, each tiny magnetic field is canceled by one that points in the opposite direction, for a total effect of no observable or cumulative field polarity. The two electric forces of the point charges in Coulomb’s law would cancel each other and produce an electric force (F) of zero. Once the electric force is zero, this would cause the entire electric field (E) to be zero (or the principle of superposition of electric fields). (i.e. E = F0 / q0 = E1+E2+E3+… = 0 @ F0 = 0)
The magnetic field’s specific direction is described as Flux. While reading the disk, the head becomes a flux transition detector, emitting voltage pulses whenever it crosses a transition. Areas of no transition generate no pulse. {INCLUDE DIAGRAM}
In conclusion, the magnetic disk, or hard disk, has many interesting and concrete physics principles. The previous paragraphs have cited explicit examples mainly of Rotational Kinetic Energy, Inertia, Magnetic Fields, Liminar Flow, Coulomb’s Law, Principle of Superposition of Electric Fields, and Flux. Using physics in computers and computer science is an important procedure, which will help engineers improve on future computer components. Again, the topic of magnetic disks is one that involves many physics related phenomenon.

Bibliography

Clements, Alan. The Principles of Computer Hardware. New York : Oxford University Press, 1985.

Freedman, & Young. University Physics. Canada: Addison Wesley Longmann, Inc. 10th ed. 2000.

Muller, Scott. Upgrading and Repairing PCs. Indianapolis: Que Coroporation. 6th ed. 1996.

Patterson, A. David; Hennessy, L. John. Computer organization and design : the hardware/software interface /. San Mateo, Calif. : Morgan Kaufmann, c1994.

Patterson, A. David; Hennessy, L. John. Computer organization and design : the hardware/software interface /. San Mateo, Calif. : Morgan Kaufmann, 2nd ed. c1994.

Stallings, William. Computer organization and architecture : principles of structure and function. New York : Macmillan ; London : Collier Macmillan, c1990.