When light comes to the different medium, the light will be bent.
When light from less dense media come to more dense (denser) media, the light will be bent approaching the normal line ( i > r ).
When light from denser (more dense) media come to less dense media, the light will be bent away from the normal line ( i < r )
Law of Refraction
1.The incident ray (i), normal and the refracted ray (r) all lie in the same plane.
2.For two particular media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant (sin i/sin r = constant = n =refractive index) or mathematically
n1 sin i = n2 sin r
1 refers to where the incidence ray comes and 2 refers to where the refracted ray comes.
The refracted index for air, usually taken as 1
Refractive index also can be calculated as V air / V medium
When we see through a pool, its depth will look shallower, by knowing its refractive index, we can calculate the apparent depth as n = real depth / apparent depth
Work Example of Refraction
When we see through a pool, its depth will look shallower, by knowing its refractive index, we can calculate the apparent depth as n = real depth / apparent depth
Work Example of Refraction
State whether this statement true or false
1. The light comes from the air to the water can be bent up to 30 degree depends on the angle of incidence.
2. The light comes from the denser medium to the less dense medium will be bent away from the normal line.
3. The shining diamond occurs because refraction.
4. Total internal reflection only occurs when the angle of refraction is bigger than critical angle.
5. Rainbow is a sample of dispersion due to different medium of light transmission during rain
6. Calculate and sketch the ray from air to plastics (refractive index 1.5) as below
7. If the incident ray comes with the frequency of 1014 Hz then find the frequency, wavelength and speed of the refracted ray
Total Internal Reflection
When the light travels from the denser medium to a less dense medium, the light will be bent away from the normal line. As the angle of incidence is increased further, it will reach the critical angle ( angle of incidence which will create angle of refraction value as 90 degree ). Consequently, when the incidence light reach over the critical angle, total internal reflection will occur. For example, by taking the normal critical angle of a glass is 41 degree, we can know that when the angle of incidence light less than or equal to 41 degree,refraction will occur, on the contrary, total internal reflection will due. Observe the figure below from left to the right, when the angle of incidence is 30 degree(less than its critical angle), the light will be refracted away from the normal line. When angle of incidence equal to critical angle, the light will be refracted as far as 90 degree. Last, when the angle of incidence is 45 degree (more than its critical angle), the light will be reflected inside the medium (total internal reflection).
1. The light comes from the air to the water can be bent up to 30 degree depends on the angle of incidence.
2. The light comes from the denser medium to the less dense medium will be bent away from the normal line.
3. The shining diamond occurs because refraction.
4. Total internal reflection only occurs when the angle of refraction is bigger than critical angle.
5. Rainbow is a sample of dispersion due to different medium of light transmission during rain
6. Calculate and sketch the ray from air to plastics (refractive index 1.5) as below
7. If the incident ray comes with the frequency of 1014 Hz then find the frequency, wavelength and speed of the refracted ray
Total Internal Reflection
When the light travels from the denser medium to a less dense medium, the light will be bent away from the normal line. As the angle of incidence is increased further, it will reach the critical angle ( angle of incidence which will create angle of refraction value as 90 degree ). Consequently, when the incidence light reach over the critical angle, total internal reflection will occur. For example, by taking the normal critical angle of a glass is 41 degree, we can know that when the angle of incidence light less than or equal to 41 degree,refraction will occur, on the contrary, total internal reflection will due. Observe the figure below from left to the right, when the angle of incidence is 30 degree(less than its critical angle), the light will be refracted away from the normal line. When angle of incidence equal to critical angle, the light will be refracted as far as 90 degree. Last, when the angle of incidence is 45 degree (more than its critical angle), the light will be reflected inside the medium (total internal reflection).
Total internal reflection can be seen in a optics cable, the benefit of using total internal reflection is that it will transmit quickly and clearly.
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