Huygens’ Principle Wavefront: the locus of the points which are in the same phase. Example: a small stone dropped in a calm pool of water. Circular ripples spread out from the point of impact, each point on the circumference of the circle (whose center is at the point of impact) oscillates with the same amplitude and same phase and thus we have a circular wavefront. Each point of a wavefront is a source of secondary disturbance and the wavelets emanating from these points spread out in all directions with the speed of the wave. The envelope of these wavelets gives the shape of the new wavefront.
Duality in Nature: Rays of light can be regarded as streams of (very small) particles emitted from a source of light and traveling in straight lines. Geometrical Optics: when wavelength can be neglected as compared with dimension of the relevant components in the optical system. Light also takes a wave motion, spreading out from a light source in all directions and propagating through an all-pervasive medium. Light can be viewed as the electromagnetic radiation in a particular region of spectrum. Physical Optics: when wave character can be ignored.
Law of Reflection When a ray of light is reflected at an interface dividing two uniform media, the reflected ray remains within the plane of incidence includes the incident ray and the normal to the point of incidence. Law of Refraction (Snell’s Law) When a ray of light is refracted at an interface dividing two uniform media, the transmitted ray remains within the plane of incidence and the sine of the angle of refraction is directly proportional to the sine of the angle of incidence. SILAHKAN KLIK DOWNLOAD DISINI
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