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when light rays enter a new medium in a new angle it may speed up or speed down
The light rays will refract towards the normal of the medium and emerge out at the same angle.
Reflection is a change of the angle of light without a change of medium. Refraction is a change of the angle of light with a change of medium.
Light changes speed as it moves from one medium to another (for example, from air into the glass of the prism). This speed change causes the light to be refracted and to enter the new medium at a different angle. The degree of bending of the light's path depends on the angle that the incident beam of light makes with the surface, and on the ratio between the refractive indices of the two media. The refractive index of many materials (such as glass) varies with the wavelength or color of the light used, a phenomenon known as dispersion. This causes light of different colors to be refracted differently and to leave the prism at different angles, creating an effect similar to a rainbow.
The change in speed causes the light to bend. If it is travelling from an optically dencer to an optically rarer medium the ray will bend away from the normal. But if it is travelling from an optically rarer to an optically denser medium then it will bend towards the normal.
when light rays enter a new medium in a new angle it may speed up or speed down
Light rays bend when they enter a new medium at an angle because they either slow down or speed up. They speed up the most if they are in a vacuum.
The light rays will refract towards the normal of the medium and emerge out at the same angle.
The change in speed causes the light to bend. If it is travelling from an optically dencer to an optically rarer medium the ray will bend away from the normal. But if it is travelling from an optically rarer to an optically denser medium then it will bend towards the normal.
Reflection is a change of the angle of light without a change of medium. Refraction is a change of the angle of light with a change of medium.
It is only possible if light enters another medium with an angle other then 90. WHen it does so then some part of light enters the medium first and it slows down first while the other part enter after a while and slows down later. This time gap .For much better understanding see... http://www.youtube.com/watch?v=Tyzci1qTVL8
Light changes speed as it moves from one medium to another (for example, from air into the glass of the prism). This speed change causes the light to be refracted and to enter the new medium at a different angle. The degree of bending of the light's path depends on the angle that the incident beam of light makes with the surface, and on the ratio between the refractive indices of the two media. The refractive index of many materials (such as glass) varies with the wavelength or color of the light used, a phenomenon known as dispersion. This causes light of different colors to be refracted differently and to leave the prism at different angles, creating an effect similar to a rainbow.
The change in speed causes the light to bend. If it is travelling from an optically dencer to an optically rarer medium the ray will bend away from the normal. But if it is travelling from an optically rarer to an optically denser medium then it will bend towards the normal.
when light travels from rarer medium(which has relatively lower density) to a denser medium(which is of relatively higher density) the angle of incident light and refracted light is less than 180 degree(when the angle is considered at the point of incidence) and when the light travels from a denser to a rarer medium the angle will be greater than 180 degree.
When light travels through a transparent medium it is slowed down according to the refractive index of the medium. Also if light is incident at an angle onto a surface of such a material, the light rays are bent or refracted by an angle at the boundary of the material, the angle again depending on the refractive index.
Critical angle of a medium depends on refractive index of the medium. Different colors of light have different wavelengths have different refractive indices.
Light bends towards the denser medium. If the light passes at an angle from air into water the angle will increase. An object underwater will appear closer to you than it actually is when you look down into the water at an angle.