The drawing shows three layers of different materials, with air above and below
ID: 1267494 • Letter: T
Question
The drawing shows three layers of different materials, with air above and below the layers. The interfaces between the layers are parallel. The index of refraction of each layer is given in the drawing. Identical rays of light are sent into the layers, and light zigzags through each layer, reflecting from the top and bottom surfaces. The index of refraction for air is nair = 1.00. For each layer, the ray of light has an angle of incidence of 74.0?. For the cases in which total internal refection is possible from either the top or bottom surface of a layer, determine the amount by which the angle of incidence exceeds the critical angle.
Layer a the top surface ?? = Layer b the top surface ?? = Layer b the bottom surface ?? = Layer c the bottom surface ?? =Explanation / Answer
Whenever a ray enters from glass medium to air medium, the light is reflected as well as refracted. That is both reflection and refraction take place.
When the angle of incidence (in glass) is zero, the angle of refraction (in air) is also zero. This is called normal incidence and there is no reflection inside the glass.
When the angle of incidence is increased from zero, there is both reflection and refraction. For refection the angle of incidence is equal to the angle of reflection and for refraction the angle of refraction (in air) is greater than the angle of incidence (in glass).
When the angle of incidence equals the critical angle there is both reflection and refraction. For refection the angle of incidence is equal to the angle of reflection and for refraction the angle of refraction (in air) equals 90 degree.
When the angle of incidence exceeds the critical angle, then there is no refraction and there is only reflection and the angle of incidence is equal to angle of reflection.
The ray not only is reflected internally but also is totally reflected, i.e., there is no refraction. That is there is TOTAL internal reflection.
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