What is polarity? Explain the Brestster principle
Answers
Explanation:
the property of having poles or being polar.
"it exhibits polarity when presented to a magnetic needle"
the relative orientation of poles; the direction of a magnetic or electric field.
plural noun: polarities
"the magnetic field peaks in strength immediately after switching polarity"
the state of having two opposite or contradictory tendencies, opinions, or aspects.
The Principle of Polarity embodies the idea that everything is dual, everything has two poles, and everything has its opposite
Define Polarity
“A state or a condition of an atom or a molecule having positive and also negative charges, especially in case of magnetic or an electrical poles.”
Polarity, in general, refers to the physical properties of compounds such as boiling point, melting points, and their solubilities. The polarity of bonds mainly arises from the act between molecules and atoms with various electronegativities.
Polarity
Polarity in Sodium Chloride
Moving on, usually, the term Polarity is used in areas like magnetism, electricity, and signalling of electronic devices. Consider an electromotive force (EMF) or an electric potential, acting between two points. Here the points or poles as they are commonly known as has more number of electrons than the other. The pole having more electrons possesses a negative polarity whereas the other end has a positive polarity.
Consider the below example
Hydrogen Fluoride
In an H-F bond, the fluorine atom is said to be more electronegative than that of the Hydrogen atom. The electrons eventually spend more time at the Fluorine atom. Hence this F atom slightly becomes negative whereas the Hydrogen atom tends to become slightly positive.
Brewster's Law
Brewster’s law is a relationship of light waves at the maximum polarization angle of light. This law is named after Sir David Brewster, a Scottish physicist, who proposed the law in the year 1811. The law states that the p-polarized rays vanish completely on different glasses at a particular angle.
Further, the polarization angle is also called Brewster’s angle. It is an angle of incidence where the ray of light having a p-polarization transmitted through a dielectric surface that is transparent without any reflection. While the unpolarized light at this angle is transmitted, the light is reflected from the surface.
Brewster's Law
Brewster was able to determine that the refractive index of the medium is numerically equal to the tangent angle of polarization. To know more about Brewster’s Law Formula.
μ=tani
Where,
μ = Refractive index of the medium.
i = Polarization angle.
From Snell’s Law:
μ=sinisinr……..1
From Brewster’s Law:
μ=tani=sinicosi……..2
Comparing both formulas: 1 and 2
cosi=sinr=cos(π2−r)
i=π2–r,or i+r=π2
As, i+r=π2<ABC is also equal to the π2. Therefore, the reflected and the refracted rays are at right angles to each other.
Application of Brewster’s Law
One general example of the application of Brewster’s law is polarized sunglasses. These glasses use the principle of Brewster’s angle. The polarized glasses reduce glare that is reflecting directly from the sun and also from the horizontal surfaces like road and water. Photographers also use the same law to reduce the reflection from reflective surfaces by using a polarizing filter for the lens.