what is refraction:
Refraction is a change of direction of a wave. Any type of wave can be refracted. Refraction can occur when the speed of a wave changes, as it moves from one environment (medium) to another.
After refraction, the wave has the same frequency but a different speed, wavelength and direction. When a wave enters a new environment, its change in speed will also change its wavelength
If the wave enters the new environment at any angle other than normal to the boundary, then the change in the wave speed will also change its direction. This is most easily shown with water waves.
Refraction of light
refraction is an effect of a wave when it enters a medium where its speed is different.The refraction of light when it passes from a fast medium to a slow medium affect the light ray . The amount of bending depends on the indices of refraction of the two media and is described quantitatively by Snell's law.
where θ 1 and θ 2 are the angles between the normal (to the interface) and the incident and refracted waves, respectively. This phenomenon is also associated with a changing speed of light as seen from the definition of index of refraction provided above which implies:
where v1 and v2 are the wave velocities through the respective media. Various consequences of Snell's Law include the fact that for light rays travelling from a material with a high index of refraction to a material with a low index of refraction, it is possible for the interaction with the interface to result in zero transmission.
Index of refraction
The light slowing factor is called the index of refraction for example glass has n = 1.52, meaning that light travels about 1.5 times slower in glass than in vacuum. Below are some other examples:
water has n = 1.33
air has n = 1.00028
vacuum is n = 1.00000 (speed of light at full capacity)
Total internal reflection
When light travels from a medium with n1 > n2, there is an angle, called the critical angle θc, at which all the light is reflected and none is transmitted. This process is known as total internal reflection. As light signals travel down a fiber optic cable, it undergoes total internal reflection allowing for essentially no light lost over the length of the cable.The critical angle occurs when θ2= 90 degrees
Reflection
Reflection is the abrupt change in the direction of propagation of a wave that strikes the boundary between two different media. At least some part of the incoming wave remains in the same medium.
Curved Mirror
the curved mirrors are partial spherical surfaces. The line of symmetry of the curved mirror is called as the principal axis of the mirror. The radius of the sphere is called the radius of curvature and half radius of curvature of the mirror is called the focal length of the mirror. The focal length is also defined as the distance from the mirror along the principal axis to the point called focus of the mirror.
Concave Mirror
Concave mirrors are used in certain types of astronomical telescopes called reflecting telescopes. The mirrors condense lots of light from faint sources in space onto a much smaller viewing area and allow the viewer to see far away objects and events in space that would be invisible to the naked eye.Light rays travel towards the mirror in a straight line and are reflected inwards to meet at a point called the focal point. Concave mirrors are useful for make-up mirrors because they can make things seem larger. This concave shape is also useful for car headlights and satellite dishes.
Convex mirrors
Convex mirrors curve outwards, like the outside of a balloon.
Parallel rays of light strike the mirror and are reflected outwards. If imaginary lines are traced back, they appear to come from a focal point behind the mirror.
Convex mirrors are useful for shop security and rear-view mirrors on vehicles because they give a wider field of vision.
Concave Mirror Reflection
An Image is the location in space where it appears that light diverges from. Any observer from any position who is sighting along a line at the image location will view the object as a result of reflected light. Each observer sees the image in the same location regardless of the observer's location. As the observer sights along a line, a ray of light is reflecting off the mirror to the observer's eye. Thus, the image location of an object is to determine the location where reflected light intersects.
The diagram below shows an object placed in front of a convex mirror. Light rays originating at the object location are shown approaching and subsequently reflecting from the mirror surface. Each observer must sight along the line of a reflected ray to view the image of the object. Each ray is extended backwards to a point of intersection - this point of intersection of all extended reflected rays is the image location of the object. (focal point (F) that is located along the principal axis, midway between the mirror's surface and the center of curvature)
there were two rules of reflected for concave mirrors. They are:
Any incident ray travelling parallel to the principal axis on the way to a concave mirror will pass through the focal point upon reflection.
Any incident ray passing through the focal point on the way to a concave mirror will travel parallel to the principal axis upon reflection.
Summary
To sum up, we were searching about the laser and how it works and during the course I learned about the mirrors which used in laser and it make me interested about convex mirror and Concave mirror and the reflation on them and also want to know refraction. Thus, I think I found out the answer of my question about refraction in different environment. Beside, I learn about reflection and convex and concave mirror .
Reference:
1. Curved mirror[online]
URL: http://physics.tutorvista.com/light/curved-mirror.html Access 14 December 2014
2. Refraction [Online]
URL: http://en.wikipedia.org/wiki/Refraction Access 14 December 2014
3. Refraction [Online]
URL: http://www.physicsclassroom.com/class/refrn Access 14 December 2014
4.Geometrical optics [Online]
URL: http://en.wikipedia.org/wiki/Geometrical_optics Access 14 December 2014
5. Reflection [Online]
URL: http://www.physicsclassroom.com Access 14 December 2014