Refractive Index: We know that when light passes obliquely from one medium to another, it changes direction in the second medium. The extent to which change in direction takes place in the given set of a medium is termed as refractive index. Refraction Of Light Consider a ray of light passing from medium 1 to medium 2 as shown in fig. v1= speed of light in medium 1 v2= speed of light in medium 2 The refractive index of medium 2 with respect to 1 can be written as below:

  Snell's law Snell’s law is defined as “ The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for the light of a given colour and for the given pair of media”.  Snell’s law formula is expressed as: Where  i  is the angle of incidence and  r  is the angle of refraction.  This constant value is called the  refractive index  of the second medium with respect to the first.

  Refraction is the bending of a wave when it passes from one medium to another. The bending is caused due to the differences in density between the two substances. Defining Refraction “Refraction is the change in the direction of a wave passing from one medium to another.” Refraction of light is one of the most commonly observed phenomena, but other waves like sound waves and water waves also experience refraction. Refraction makes it possible for us to have optical instruments such as magnifying glasses, lenses and prisms. It is also because of the refraction of light that we are able to focus light on our retina. Refraction in Nature Why do stars twinkle? Did you know that the twinkling effect of stars is due to atmospheric refraction? The starlight undergoes several refractions while reaching the Earth. This atmospheric refraction occurs in a medium of gradually changing refractive index. Causes of Refraction Change of Speed Results in Change in Direction A light ray refracts w...

  Reflection W hen a ray of light approaches a smooth polished surface and the light ray bounces back, it is called the reflection of light. The incident light ray that land on the surface is reflected off the surface. The ray that bounces back is called the reflected ray. If a perpendicular were drawn on a reflecting surface, it would be called normal. The figure below shows the reflection of an incident beam on a plane mirror. Here, the  angle of incidence  and angle of reflection are with respect to normal and the reflective surface. Laws of Reflection The  laws of reflection  determine the reflection of incident light rays on reflecting surfaces, like mirrors, smooth metal surfaces and clear water. Let’s consider a plane mirror as shown in the figure above. The law of reflection states that The incident ray, the reflected ray and the normal all lie in the same plane The angle of incidence = Angle of reflection

  Light Light is a form of electromagnetic radiation emitted by hot objects like lasers, bulbs, and the sun. Light is a kind of kinetic energy that enables the human eye to see or make things visible. Light energy is a form of electromagnetic radiation that can be seen by the human eye. Properties of light Following are the properties of light: Reflection of light:  Every light follows the law of reflection which states that the angle of incidence is equal to the angle of reflection. Refraction of light:  Refraction of light takes place when the light ray changes its velocity it passes from one medium to another. Index of refraction is used as a means to measure how much light refracts. Dispersion:  Dispersion of light is defined as the process in which the white light separates into different colours based on its wavelength when passed through a glass prism.   Diffraction:  The effect of bending light around small obstacle corners and hence its encroachmen...