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Compare and contrast reflection and refraction?science

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maruma | Student, Grade 9 | (Level 2) eNoter

Posted February 23, 2010 at 8:27 AM via web

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Compare and contrast reflection and refraction?

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krishna-agrawala | College Teacher | (Level 3) Valedictorian

Posted February 23, 2010 at 11:18 AM (Answer #1)

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When light passes from from one type of medium to another type of medium, the medium being composed of substances like air, glass or water, one or both of two different types of changes take place in the direction of the ray of light as it strikes the surface separating the two mediums. These changes in direction of light are called reflection and refraction.

Part of the light may not enter the new medium at all. Instead it may bounce back in original medium. This change in direction of light within a medium without entering another medium is called reflection. In the process of refraction the light enters from one medium to another instead of being bounced of the surface. When this happens the direction of the light changes to some extent, but not completely reversed. The exact degree and orientation of change in direction depends on the angle at which the ray strikes the surface separating the two mediums and the comparative refractive indices of the two medium.

As can be seen from the description above in case of reflection the light continues to travel in the original medium. In case of refraction the light travels from one kind of medium in to another.

In case of reflection the angle the original ray of light makes with the the normal to the reflecting surface is equal to the angle made bu reflected surface although on the other side of normal. In contrast in case of reflection the angles with the normal made by original and refracted ray are different.

In case of refraction there is no change in direction of light that strikes the refracting surface at right angle. In case of reflection the direction of original and reflected light is exactly opposite when the striking the reflecting surface at right angles.

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted February 24, 2010 at 3:11 AM (Answer #2)

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Refraction is changing of light direction when crossing from a transparent medium to another. Because light travels with
different speeds in different environments, it has to change the speed at passing from one medium to another.If a beam of light reaches the surface at an angle, then the light on the
beam side,which is reaching first the surface of separation, is forced to slow or to increase their speed before the light of the other side to reach the new environment.This causes bending, or refraction of the beam at separation surface.

For example light reflected by an object under water passes first through the water and then by air to reach the eye of an observer. From some angles,a partially submerged object appears bent where it enters in water, because light coming from under the water is refracted.

Refractive index of an environment is the ratio between velocity light in vacuum and the speed of light in that environment.

Reflection also occurs when light reaches the surface of separation between two environments .Some of the light that reaches the surface of separation will be reflected in the first environment. If the light reaches separation surface at an angle, then the light is reflected on the same angle, similar how to a ball jumps when it reaches the ground.Light that is reflected from a flat surface, such as surface between air and a lake, will form a mirror image.Light reflected from a curve surface  can be focused in a point, a line, or in an area, so depending on the curvature of the surface.

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neela | High School Teacher | (Level 3) Valedictorian

Posted February 23, 2010 at 11:57 PM (Answer #3)

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Comparision: Both reflection and refractions is phenomenon related with wavemotion of sound, electromagnetic waves icluding light.

1a The sound or light or wave  bounce back in reflection. The incident ray ,and the point of incidence, the normal drawn at the point of incidence and the relected ray reflected ray are all in the same plane. 1b. In refraction also the incident ray, the point of incidence, the normal drawn at the point of incidence and the refracted ray are all in the same olane.

Contrast:

2a.In reflection, the angle of incidenct ray with the normal = angle of reflected ray with the normal 2b. In refraction, the angle i, of incidence  with the normal and the angle r of refracted ray  are different and they obey Snell's law.

sin i / sin r = velocity of incidence/ velocity of refraction =

3a In reflection the image gets the lateral inversion 3b In refraction the image  gets change in vertical plane or inversion etc.

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