Definition. The property in which the light passes through a medium is known as a transparent property. The medium that allows light to pass through it is known as a transparent medium. The medium that allows only a fraction of light to pass through them is known as a translucent medium.

It has been the dominant medium in easel painting since the renaissance. They can support luminous colors and sometimes look very close to oil paintings in their final effect.

The oldest painting medium Chemically watercolors are pigments made from ground minerals and dyed inert powder, held together generally with gum arabic made from the acacia tree. Watercolors capture luminosity and offer a range equal to and often exceeding that of other mediums.

Light can travel in three ways from a source to another location: (1) directly from the source through empty space; (2) through various media; (3) after being reflected from a mirror.

Large telescopes use reflection to form an image of stars and other astronomical objects. Figure 1. The law of reflection states that the angle of reflection equals the angle of incidence—θr = θi. The angles are measured relative to the perpendicular to the surface at the point where the ray strikes the surface.

Figure 1.5 The law of reflection states that the angle of reflection equals the angle of incidence—θr=θi. The angles are measured relative to the perpendicular to the surface at the point where the ray strikes the surface.

According to first law of reflection incident and reflected angles are equal. So, reflected angle will be 30 degrees. Reflected angle and angle B together make up the angle between normal and the surface that is 90 degrees. So, Angle b = (90 – reflected angle), which is (90-30) = 60 degree.

Angle of reflection: The angle between the normal and the reflected ray is called the angle of reflection. It is denoted as r. Law 1 : The incident ray, the normal at the point of incidence and the reflected ray all lie in the same plane.

In optics, angle of incidence can be defined as the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence (called as normal).

An incident ray is a ray of light that strikes a surface. The angle between this ray and the perpendicular or normal to the surface is the angle of incidence. The reflected ray corresponding to a given incident ray, is the ray that represents the light reflected by the surface.

Refractive Index (Index of Refraction) is a value calculated from the ratio of the speed of light in a vacuum to that in a second medium of greater density. The refractive index variable is most commonly symbolized by the letter n or n’ in descriptive text and mathematical equations.

Relative refractive index– It is the ratio of speed of light in one medium to the speed of light in another medium • Absolute refractive index– It is the ratio of light in vacuum to the speed of light in another medium.

The refractive index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is v = c/n, and similarly the wavelength in that medium is λ = λ0/n, where λ0 is the wavelength of that light in vacuum.

It is mostly applied for identify a particular substance, confirm its purity, or measure its concentration. Generally it is used to measure the concentration of a solute in an aqueous solution. For a solution of sugar, the refractive index can be used to determine the sugar content (Brix degree).

The two factors which affect the value of the refractive index are:

• Temperature. Refractive index values are usually determined at standard temperature.
• Wavelength of light. The refractive index varies with wavelength linearly because different wavelengths interfere to different extents with the atoms of the medium.

The lower the refractive index, the faster the velocity of light. Medium A has the smaller refractive index. Light will travel faster through medium A at a velocity equal to the speed of light divided by the refractive index.

The absolute refractive index is defined as the ratio of the speed of light in vacuum and in the given medium. The absolute refractive index should never be less than 1.