An Elementary Text-book of Physics: Light |
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Common terms and phrases
adjust angle of incidence appears beam called centre of curvature colour compared cone considered constituent construction convention converging corresponding denote determined deviation diameter direction directly distance diverging draw edge emergent entering equal ether evidently exactly Experiment explained faces figure flame focal length follows formed front given gives glass greater Hence illuminated inches incident ray increases intensity lens less lies looking material measure medium method mirror moves normal noted noticed object obtained optical parallel passing path pencil placed plane plate portion position practically principal axis principal focus prism produced ratio reflected refracted ray relation relative represent respectively screen seen separation shadow sheet shown in Fig side similar Similarly source of light spherical surface takes usually virtual wave length
Popular passages
Page 128 - When a ray of light passes from one medium to another, it is refracted so that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the velocities in the two media.
Page 128 - ... that the ratio of the sines of the angles of incidence and refraction is constant for refraction in the same medium, was effected by Snell and Descartes.
Page 46 - The angle that the incident ray makes with the normal at the point of incidence is called the angle, of incidence, and the plane of this angle is the plane of incidence.
Page 120 - Philosophers have put forward the thesis that the validity or non-validity of Euclidean geometry cannot be proved by empirical observations. It must in fact be granted that in all such observations essentially physical assumptions, such as the statement that the path of a ray of light is a straight line and other similar statements, play a prominent part. This merely bears out the remark already made above that it is only the whole composed of geometry and physics that may be tested empirically.
Page 49 - The incident ray, the reflected ray, and the normal to the reflecting surface at the point of incidence lie in the same plane, 2.
Page 128 - The incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane.
Page 120 - ... the refracted ray ; and the acute angles which they make with the normal to the surface of separation at the point of incidence, are called the angles of incidence and refraction, respectively. The angles of incidence and refraction lie always in the same plane, and their sines are to one another in an invariable ratio. This is the fundamental law of refraction.