Polarization definitionin Chemistry

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

Now that we’ve explored the different types of ND filters let’s dive into how to use them to their maximum potential.Controlling ExposureThe primary use of ND filters is to control exposure. For instance, if you’re shooting a waterfall or a flowing stream, you may want to use a slower shutter speed to capture the water’s motion. However, doing so without an ND filter would result in overexposed images. By using an ND filter, you can reduce the amount of light entering the lens, allowing for a slower shutter speed.Creating Motion Blur and Capture a Sense of TimeND filters are useful in creating motion blur in your images. By using a slow shutter speed, you can capture the movement of clouds, water, or any other subject that moves, resulting in a visually appealing image.Balancing ExposureND filters are perfect for balancing exposure when shooting a scene with a significant difference in brightness between the foreground and the sky. By using a graduated ND filter or GND, you can position the denser part of the filter over the brighter area, achieving a balanced exposure.Shooting Wide Aperture in Bright LightShooting wide aperture in bright light can be challenging, as it can result in overexposed images. Using an ND filter, you can reduce the amount of light entering the lens, allowing for a wider aperture and a shallower depth of field.

Neutral density filters are an essential tool in every photographer and videographer’s toolkit. By understanding the different types of ND filters and how to use them, you can unlock their full potential and enhance your photography and videography skills. Remember to experiment with different densities and filter types to achieve the desired effect in your images. With a little practice, you’ll be able to master the art of using ND filters and take your photography and videography to the next level.

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.

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.

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

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

Polarization definition

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

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

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.

There are various types of ND filters, each with its unique characteristics and applications.Solid ND FiltersSolid ND filters are the most common type of ND filters. They are available in different densities, ranging from ND2 (1 Stop) to ND100K(20 Stop), with each density value indicating the number of stops by which the filter reduces light. Solid ND filters are useful in situations where you want to achieve a longer exposure time during the day or when using a wide aperture.Graduated ND Filters Graduated ND filters have a graduated density that varies from one end to the other, with one side being denser than the other. These filters are useful when shooting a scene with a significant difference in brightness between the foreground and the sky. By positioning the denser part of the filter over the brighter area, you can achieve a balanced exposure.Variable ND FiltersVariable ND filters allow you to adjust the density of the filter by rotating the filter ring. These filters are perfect for situations where lighting conditions are continually changing, such as shooting in a forest or near the water.

Polarization of lightnotes PDF

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.

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

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.

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.

Polarizationby reflection

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

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.

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

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.

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.

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

Polarisation meaning in Physics

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 neutral density filter or ND Filter is a camera accessory that reduces the amount of light entering the camera lens, allowing for a longer exposure time. The filter’s primary function is to balance the exposure of a scene by reducing the brightness of the brightest elements without affecting color or contrast. ND filters come in different levels of density, which determine the amount of light that passes through the filter.ND Filters enable you to capture sharper images and photograph at larger apertures allowing you to control diffraction.  For example, if the subject is a waterfall during the day and the target shutter speed is 2 seconds to smooth out the flowing water, without an ND the aperture will be small ie f/22 and this will cause a reduction in sharpness due to diffraction. With an ND Filter, it will allow you to reduce the aperture ie f/10 to get a sharper image.

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.

Polarized and unpolarizedlight

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.

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 (-).

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.

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.

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

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.

Plane polarizedlight definition

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

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

Polarization of light definitionphysics

Smoothing or softening of waterBy using an ND filter, you can achieve longer shutter speeds, which in turn creates a blur effect on moving water. This effect is commonly used in landscape photography, particularly when capturing waterfalls or streams. The result is a smooth, flowing image that creates a sense of movement and tranquility.Emphasizing water flowSimilarly, ND filters can also be used to emphasize the flow of water in an image. By choosing the appropriate filter strength, you can create a balance between the blur effect and the detail of the water. This technique is particularly useful in capturing the energy and power of ocean waves.Smoothing or softening of cloudsND filters can also be used to create a dreamy effect on clouds. By using a long exposure, the clouds will appear to move across the sky, creating a sense of movement and dynamism. This technique is particularly useful in landscape photography, where a dramatic sky can add depth and dimension to an image.Emphasizing movement in an imageND filters can also be used to emphasize movement in an image. By using a long exposure, you can create a blur effect on moving subjects, such as people, cars, or animals. This technique can add a sense of energy and motion to an image, making it more dynamic and interesting.Creating cloud movementIn addition to creating a blur effect on clouds, ND filters can also be used to create a sense of movement and direction in the clouds. By using a filter with a longer exposure time, you can create streaks of cloud movement that add a sense of drama and tension to an image.Removing moving objectsLastly, ND filters can be used to remove moving objects from an image. By using a long exposure, anything that moves within the frame will be blurred or disappear entirely. This technique is particularly useful in busy scenes, such as cityscapes or tourist attractions, where you want to remove distracting elements from the image.

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

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!

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

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.

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.

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.