NOTE:pakibasa un mga note muna a. tnx tnx. Ehe.:D ANSWERS TO GUIDE QUESTIONS 1. If the transparent material has an index of refraction of 1.2, what is the angle of incidence beyond which total internal reflection occurs? At critical angle
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Critical angle is the angle of incidence by which the refracted ray would be refracted perpendicular to the normal line. Thus, this implies that if the angle of incidence exceeds the angle 56.44⁰, there would be a total internal refraction. 2. Is it possible for the critical angle to exist when light goes from water (n=1.33) into glass (n=1.5)? Explain your answer. No. Critical angle only exists when a light enters from a medium to a less dense medium. On this example, the light enters from water to glass which is not denser than water. Also, we can prove this from the equation
, water being the first medium and the glass being the second.
, yielding an improbable answer. PROBLEMS 1. Light travelling in a medium with a speed of 1.5 x 108 m/s, it strikes the surface of a transparent material where it travels at a speed of 2 x 108 m/s. If the incident angle is 36.86°, find the angle of refraction and the critical angle between the two media. Computing for the index of refraction of the two media,
Computing for the angle of refraction,
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Computing for the critical angle,
NOTE:eei rach. Paki aus nlan un mga box box. Wlang box dun. Aha. Dko lan maaus un sa word.xD aha. Bhala kna.:) pos paki box uli un mga final answers. Mdamiing salamaat. Tpos un mga m/s pla. Pkipalitan ng m/s wag . thanks 2. A ray of light in air, incident at an angle of 60° on top of a transparent surface, is refracted and reflected partly. It is observed that the refracted and reflected rays are perpendicular to each other. Find the index of refraction and the velocity of light in transparent surface. NOTE: eei. Palagay ng space sa left side. Ddrawingan ko p kc ih. Tnx. Ket ¼ ng buong working space. Computing for the index of refraction of the medium,
Computing for the velocity of light in the transparent surface, v
3. Light strikes the surface of a transparent material at an angle of incidence of 30°. If the refracted angle in the transparent material is 20°, what is the speed of light in the material? Computing for the index of refraction of the medium,
Computing for the velocity of light in the transparent surface, v
ANALYSIS 1. Why can’t a material medium have an index of refraction less than 1.00? Index of refraction, by definition, is the ratio of the velocity of light in a vacuum over the velocity of light in any medium,
. It is also known that the velocity of air in a vacuum is always greater than the
velocity of light in any given medium. Thus, in the equation, the numerator is always greater than the denominator, always yielding a result of greater than 1.00. 2. Does the angle of incidence affect the index of refraction of a material? Support your answer. No. Index of refraction is a unique property of materials. Thus, no two materials can have the same index of refraction. It is also an intensive property, thus, it doesn’t change though some external factors acts on the material. Also, the value of the index of refraction depends only on the velocity of light on the medium which in turn, depends on the density of the material. 3. What happens to the wavelength of light when it is refracted? What does this mean? As light travels from one medium to another of different density, the velocity of light as it passes through it also changes. And by definition, the velocity of a wave is also known as to be also by definition, the frequency of light doesn’t change as it changes from one medium to another. Thus, it implies that the wavelength of light either increase or decrease with direct proportion to the velocity. From the equation
, velocity is inversely proportional to the refractive index which is also known to
be direct proportional to the density of the material. Simply said, the wavelength of the light is inversely proportional to the density of the object.
CONCLUSION Refraction of light is the change in velocity of light as it passes from one medium to another medium of different density and is also the bending of light rays as they travel from one medium to another also of different density. On the fourth set of experiment on General Physics IV laboratory, the experiment ponders on such. The experiment is divided into two parts. The first part of the experiment targets to know the behavior of light as it travels from one medium to another medium of different density. It is also subdivided into two parts, the first being the determination of behavior of light as it travels from a dense medium to a less dense medium and the second being the determination of behavior of light as it travels from a less dense medium to another. On both parts, we use some concepts on trigonometry to get the value for both the angle of incidence are angle of refraction. It is found that on the first part where the second material is less dense than the first medium, the refracted ray tends to bend away from the normal line while on the second part where the second medium is denser than the first, the refracted ray tends to bend closer to the normal line. The second part of the experiment targets to determine the critical angle of light ray in glass. Critical angle, by definition, is the angle of incidence that would result the angle of refraction to bend at exactly 90⁰ from the normal line. It also indicates that for an angle of incidence greater than the critical angle, total internal reflection will occur.
