This means the law of reflection is in effect for the reflected part of the light ray, the angle of reflection equals the angle of incidence. When the light is incident to the surface of the second material, a small amount of reflection occurs even though most of the light passes through the surface interface and into the second substance. The angle of incidence equals the angle of reflection. The angle of reflection is smaller than the angle of incidence.Į. The angle of reflection is larger than the angle of incidence.ĭ. ![]() (ii) The incident ray, the normal to the mirror at the point of incidence and the reflected. ![]() The angle of refraction is equal to the angle of incidence.Ĭ. (i) The angle of incidence is equal to the angle of reflection, and. The angle of refraction is larger than the angle of incidence.ī. Which of the pairs of quantities listed below describes the light ray as it strikes and passes through the interface between the two materials? Match the descriptions below with the statement that best describes the situation.Ī part of the light ray remains inside the low refractive index material.Ī. A light ray passes from a material of low refractive index to one of high refractive index. Rays can be trapped in a waveguide through total internal reflection.12. Rays that intersect the interface between the waveguide material and the surrounding material at angles equal to or larger than the critical angle are trapped in the waveguide and travel losslessly along it. A waveguide is a length of transparent material that is surrounded by material that has a lower index of refraction. Many devices take advantage of the total internal reflection, including optical waveguides (like optical fiber). Total internal refraction is depicted in the sketch on the right. When the light impinges perpendicularly to the surface, it is reflected straight back in the source direction. These diagrams illustrate two different cases of refraction. The law of reflection states that the angle of reflection of a ray equals the angle of incidence, and that the incident direction, the surface normal, and the reflected direction are coplanar. The refractive index of the material of the plate is: 1.32 2. If the angle of incidence is increased beyond that angle, then refraction does not occur! All of the light incident on the interface is reflected back into the incident medium! The smallest angle of incidence at which total internal reflection occurs is called the critical angle, qc. When a ray of light falls on a given plate at an angle of incidence60°, the reflected and refracted rays are found to be normal to each other. (c) Measure and record the angle of incidence and angle of reflection at the convex interface Use a protractor to measure the angle of incidence, in your Fig. Eventually the refracted ray will make an angle of 90° with the surface normal. Repeat all above steps to draw the surface normal în to the concave surface at the incident point P in your Fig. If n1n2, then the angle of refraction is larger than the angle of incidence…when there is an angle of refraction! Imagine the angle of incidence getting larger and larger for the case of n1>n2. ![]() In the case of the transmitted, or refracted, ray, N1 Sinθ i = n1 Sinθ r, which is the same as Sinθ i = Sinθ r.įrom this, it is easy to see that the angle of incidence and the angle of reflection are the same! In the case of a reflected ray, nA = nB = n2 = n1, As you sight at the image, light travels to your eye along the path shown in the diagram. To view an image of an object in a mirror, you must sight along a line at the image location. According to the law of reflection, the angle of incidence equals the angle of reflection. Illustration of incident, reflected, and refracted rays. reflection is the angle between this normal and the reflected ray. The refractive index of medium 1 is n1 and of medium 2 is n2. The angle that the incident, reflected, and refracted rays make with the surface normal are called the angles of incidence, qi, reflection, qr, and refraction, qt, respectively. A refracted ray is transmitted into the second medium and travels in a different direction than the incident ray. This plane also contains the reflected and refracted rays. A plane that includes the incident ray and a line drawn normal to the surface is called the plane of incidence. In the following figure, a ray is incident on an interface between two dissimilar media. The angles in this equation are referenced to a surface normal, as is illustrated below. Predicts how the ray will change direction as it passes from one medium into another, or as it is reflected from the interface between two media. In order to follow the quickest path through a system, a ray changes direction as it travels from a medium of one refractive index to another medium that has a different refractive index. The law of reflection states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.
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