Hex keys are made by imparting the hexagon cross-section to steel wire (for example, with a drawing die), then bending and shearing.

3. Elliptical polarization is the same as circular polarization except that the amplitudes and phase differences are not the same.

For monoclinic or tetragonal crystals, we get the above result i.e., One O-ray and one e-ray can be observed. Whereas for orthorhombic, monoclinic, and triclinic crystals, there will be two E-rays

Polarisation of light definitionphysics

SPS at the time was a prominent maker of shaft hangers and collars, the latter of which were put in place with set screws. In pursuit of headless set screws with a better drive than a straight slot, Hallowell said, SPS had sourced set screws of square-socket drive from Britain, but they were very expensive.[5] (This was only 2 years after Robertson's Canadian patent.) This cost problem drove SPS to purchase its first screw machine and make its screws in-house, which led to SPS's foray into fastener sales (for which it later became well known within the metalworking industries). Hallowell said "[for] a while we experimented with a screw containing a square hole like the British screw but soon found these would not be acceptable in this country [the U.S.]. Then we decided to incorporate a hexagon socket into the screw […]."[6] Hallowell does not elaborate on why SPS found that the square hole "would not be acceptable in this country", but it seems likely that it would have to have involved licensing Robertson's patent, which would have defeated SPS's purpose of driving down its cost for internal-wrenching screws (and may have been unavailable at any price, as explained at "List of screw drives > Robertson"). The story, if any, of whether SPS's methods required licensing of Allen's 1910 patent is not addressed by Hallowell's memoir. The book does not mention which method—cold forming or linear broaching—was used by SPS in these earliest years. If the latter was used, then Allen's patent would not have been relevant.

Double refraction, also known as birefringence, is an optical property in which a single ray of unpolarized light entering an anisotropic medium is split into two rays i.e., ordinary & extraordinary rays, each traveling in a different direction.The concept of Double refraction can be observed by comparing two materials, glass and calcite.

Hex keys are measured across-flats (AF), which is the distance between two opposite (parallel) sides of the hexagon.[15]

The term "hex-head" is sometimes used to refer to this type of drive, but this use is not consistent with its more conventional use referring to external-wrenching hexagons.

The idea of a hex socket screw drive was probably conceived as early as the 1860s to the 1890s, but such screws were probably not manufactured until around 1910. Rybczynski (2000) describes a flurry of patents for alternative drive types in the 1860s to the 1890s in the U.S.,[2] which are confirmed to include internal-wrenching square and triangle types (that is, square and triangular sockets) (U.S. patent 161,390), but he explains that these were patented but not manufactured because of the difficulties and expense of doing so at the time.

Such a medium contains lots of atoms and when an unpolarized light beam strikes an atom it transfers energy to an atom. As a result, an electron in that atom starts vibrating in response to the electric component of the incident ray. Now, this vibrating electron emits E.M radiation in all directions, and this forces neighboring electrons to undergo a similar process. This phenomenon of absorption and emission of the electromagnetic radiation is known as the scattering of light.

Q: A sugar solution in a tube of length 2.0 dm produces optical rotation of 12°. Then, the sugar solution to one half of its initial concentration. If the dilute solute solution is contained in another tube of length 3.0 dm, the optical rotation produced by it will be

Optical activity is the ability of a substance to rotate the plane of polarization of a beam of light that passed through it.

Polarisationmeaning in Physics

A polarimeter is an instrument used to determine the angle through which plane-polarized light has been rotated by a given sample.

This is the reason the sky scatters more blue light than red because of the natural frequency of molecules in our atmosphere.

2. Circular polarization is when two linear components of a wave oscillate perpendicular to each other such that their amplitudes are equal.

While often used in generic terms for "hex key", the "Allen" name is a registered trademark (circa 1910) of the Allen Manufacturing Company (now Apex Tool Group) of Hartford, Connecticut; regardless, "Allen key" and "Allen wrench" are often seen as generic trademarks.

Polarizationdefinitionin Chemistry

For this experiment let’s consider that we have an unpolarized light passing through two polarizer T1 and T2, here line on polarizer shows plane of vibration i.e., the plane in which electric field vector can vibrate freely, whereas electric field perpendicular to this line will be eliminated completely.

Some hex keys have a rounded end, allowing them to be used at an angle off-axis to the screw. This type of hex key was invented in 1964 by the Bondhus Corporation[19] and is manufactured by several companies. While providing access to otherwise inaccessible screws, thinning of the tool shaft to create the rounded shape renders it weaker than the straight-shaft version, limiting the torque that can be applied; in addition, the rounded end only makes point contact with the screw as opposed to the line contact made by straight-shaft keys.

If the plane of vibration of both polarizers are parallel to each other in such polarized light from the first polarizer can easily pass through the second polarizer as shown below.

Now if we rotate second polarizer in such a way that it becomes perpendicular to first one, in this case as plane polarized light passes through second polarizer it will get eliminated since second polarizer won’t allow it to pass and hence it is called analyzer which is used to determine the plane of polarization as shown below

Now as this unpolarized light passes through the polarizer, it will polarize the light in either vertical or horizontal direction. This polarized light when again passed through a polarizer there can be two possible outcomes.

When light wave propagates it consists of vibration of electric field in all possible direction, which are perpendicular to its direction of propagation and such light waves are said to be unpolarized light.

Substances are described as dextrorotatory or levorotatory according to whether the plane of polarization is rotated clockwise or counterclockwise, respectively, as determined by viewing towards the light source. Dextrorotation is designated (+) and levorotation is designated (-).

Polarization due to scattering can be seen through the sky as we can see below. When an unpolarized beam of sunlight passes through the atmosphere the light scatters down towards earth. Also it has no vertical polarization.

P. L. Robertson of Milton, Ontario, first commercialized the square socket in 1908, having perfected and patented a suitable cold forming method, using the right material and the right die design. In 1909–1910, William G. Allen also patented a method of cold-forming screw heads around a hexagonal die (U.S. patent 960,244). Published advertisements for the "Allen safety set screw" by the Allen Manufacturing Company of Hartford, Connecticut, exist from 1910.[3]

Light passing through a calcite crystal is split into two rays as shown below. This process is called double refraction or polarization by refraction.

Polarizationdefinition

Hex socket screw heads are usually made by stamping the head with a die, plastically deforming the metal. Other ways to generate the hex socket include linear broaching and rotary broaching. Broaching the heads with a linear broach is essentially the metalworking analog of mortising wood with a mortising machine; a hole is drilled and then the corners are broached out. This operation often leaves little telltale curled chips still attached at the bottom of the socket. These are negligible for most applications.

The optical rotation is the angle through which the plane of polarization is rotated when polarized light is passed through a layer of a liquid.

The specific rotation is a characteristic property of a certain substance and is the standard measurement for the optical rotation of that substance.

Polarization of Light is a property applying to transverse waves that specify the geometrical orientation of the oscillations. Light is an electromagnetic wave in which electric and magnetic field vectors are sinusoidally perpendicular to each other as well as they are perpendicular to the direction of propagation of light waves.

In Germany the term "INBUS" is a registered trademark, originally an acronym for Innensechskantschraube Bauer und Schaurte, introduced in 1934 by the German company Bauer & Schaurte, in 2015 acquired by INBUS IP GmbH, Breckerfeld, Germany). INBUS IP GmbH was registered with the stated purpose of holding and licensing the trademark INBUS. In late 2015 to early 2016, the company sent out desist orders to companies using the name "Inbus" for hex keys.[10][11][12] Hex keys with the INBUS brand are now manufactured at HaFu Werkzeugfabrik H. J. Fuhrmann GmbH, Breckerfeld, North Rhine-Westphalia, as of 2017 accounting for 7% of the company's EUR 8 million turnover[13] and as "Unbrako" key or wrench in Scandinavia (originally a Pennsylvania company established in 1911, in 2008 acquired by Deepak Fasteners Limited).[14] In Italy, it is known as brugola, for the company Officine Egidio Brugola (established 1926). In 1946 Egidio Brugola patented an important variant with a spiral shank.

We are sure that the above Physics (Optics) notes helped you to understand the importance of Polarization of Light. Get more study notes, practice sets, and puzzles, etc. on the Testbook App. Download the app now to avail exciting offers on select subscriptions!

The two rays of light are each plane-polarized by the calcite such that the planes of its polarization are mutually perpendicular to each other as shown below.

Polarisationmeaning in Physics Electrostatics

Thus using Brewster’s law, we can conclude that polarizing angle depends on frequency of incident ray i.e., colour of incident ray hence polarizing angle will be different for different colour.

And hence from this experiment we can conclude that electric fields are vibrating perpendicular to its direction of propagation, hence light is a transverse wave.

World War II, with its unprecedented push for industrial production of every kind, is probably the event that first put most laypersons in contact with the internal-wrenching hexagon drive. (Popular Science magazine would note in 1946 "Cap screws and setscrews with heads recessed to take hexagonal-bar wrenches are coming into increasing use.")[9]

Hex keys are designated with a socket size and are manufactured with tight tolerances. As such, they are commonly sold in kits that include a variety of sizes. Key length typically increases with size but not necessarily proportionally so. Variants on this design have the short end inserted in a transverse handle, which may contain multiple keys of varying sizes that can be folded into the handle when not in use.

In his autobiography, the founder of the Standard Pressed Steel Company (SPS; now SPS Technologies, Inc.), Howard T. Hallowell Sr. presents a version of events[4] in which SPS developed a hex socket drive in-house, independently of Allen, circa 1911. From this came the Unbrako line of products. This account from Hallowell does not mention the Allen patent of 1910 nor the Allen safety set screw product line. Hallowell does describe, however, the same inspiration also mentioned in connection with Allen for a wave of adoption of the hex socket head, beginning with set screws and followed by cap screws. This was an industrial safety campaign, part of the larger Progressive Movement, to get headless set screws onto the pulleys and shafts of the line shafting that was ubiquitous in factories of the day. The headless set screws would be less likely to catch the clothing of workers and pull them into injurious contact with the running shaft.

Polarization by scattering is generally observed in liquid or gas randomness in motion of atoms. However, in perfect crystals we don’t see as good results as fluids.

Polarized and unpolarizedlight

Hex key sizes in the U.S. are defined in ANSI/ASME standard B18.3-1998 "Socket Cap, Shoulder, and Set Screws (Inch Series)".

There are three main types of polarization namely, linear polarization, circular polarization, and elliptical polarization.

The velocity and refractive index of extraordinary waves changes with direction whereas for ordinary ray velocity remains constant throughout the crystal while propagating.

Plane polarizedlight

When we restrict vibration to an electrical vector in an unpolarized light we get plane polarized light. In this the direction of vibration of electric vector and direction of light propagation are perpendicular to each other as shown below.

For calcite, one of the two rays does indeed obey Snell’s Law (angle of incidence is equal to the angle of refraction), this ray is called the ordinary ray (or O-ray). The other ray (and any ray that does not obey Snell’s Law) is an extraordinary ray (or E-ray). For normal incidence (a Snell’s law angle of 0°), the two planes of polarization are also perpendicular to the plane of incidence.

A hex key (also, hex wrench, Allen key and Allen wrench or Inbus) is a simple driver for bolts or screws that have heads with internal hexagonal recesses (sockets).

When the electric field vectors are restricted to a single plane by filtration, then the light is said to be polarized with respect to the direction of propagation and it propagates in a single plane. In this article, we are going to learn about the polarization of light, brewster’s law, double refraction, polarization by scattering. Let’s understand the Physics (Optics) phenomenon of unpolarized light first.

Standard metric sizes are defined in ISO 2936:2014 "Assembly tools for screws and nuts—Hexagon socket screw keys",[16] also known as DIN 911.[17]

However the scattered light can be unpolarized, partially polarized, or completely polarized based on the direction of the incident ray as shown below.

Polarizationof lightnotes PDF

Suppose if a pencil mark is drawn upon a sheet of paper and then covered with a piece of glass, only one image will be seen. But if the same paper is covered with a piece of calcite and the crystal is oriented in a specific direction then two marks will become visible. This is because a refracted beam acquires some degree of polarization. Most often, the polarization occurs in a plane perpendicular to the surface.

Hex keys are best known as "Allen keys" or "Allen wrenches" in English-speaking countries like the UK, Australia, Canada and the U.S. and in Spanish-speaking countries such as Spain and Mexico (The "Allen" name is a registered trademark, originated by the Allen Manufacturing Company of Hartford, Connecticut, circa 1910.[1] The brand is now owned by Apex Tool Group, LLC, which was acquired by Bain Capital in 2014).

Tamper-resistant hex screws have a protruding pin in the center of the hex recess that prevents insertion of standard hex keys; as such, they can only be fastened and removed with a special key that has a recess for the pin. A similar "center pin reject" security feature is also used on torx screws.

Hallowell said that acceptance of the internal-wrenching hexagon drive was slow at first but that it eventually caught on quite strongly.[7] This adoption occurred first in tool and die work and later in other manufacturing fields such as defense (aircraft, tanks, submarines), civilian aircraft, automobiles, bicycles, furniture and others. Concerning the dissemination of the screws and wrenches, Hallowell said "the transition from a square head set screw [Hallowell refers here to the then-ubiquitous external-wrenching square drive] to a hexagon socket head hollow set screw[,] for which had to be developed special keys or wrenches for tightening or loosening the screw, was the cause of more profanity among the mechanics and machine manufacturers than any other single event that happened. […] I am sure that the old-timers who read this book will remember this period vividly."[8] (These transitional growing pains echo those experienced many decades later with the adoption of the Torx drive).

1. Linear polarization is when the oscillation of a wave is constrained to a single plane. This is the plane of polarization.

So, as we discussed above, light is a transverse wave, and confining the plane of vibration of such a transverse wave by the principle of scattering is termed Polarization by scattering.

Hex keys are formed from a single piece of hard hexagonal steel rod, having blunt ends that fit snugly into similarly shaped screw sockets. The rods are bent to 90º, forming two arms of unequal length resembling an "L". The tool is usually held and twisted by its long arm, creating a relatively large torque at the tip of the short arm; it can also be held by its short arm to access screws in difficult-to-reach locations and to turn screws faster at the expense of torque.[1]