كتاب الفيزياء حادي عشر متقدم فصل اول امارات 2026 pdf

Virtual Images with Concave Mirrors You have seen that as an object approaches the focal point (F) of a concave mirror, the image moves farther away from the mirror. If the object is at the focal point, all reflected rays are parallel. They never meet, therefore, and the image is said to be at infinity, so the image could never be seen What happens if you move the object even closer to the mirror? The image is upright and behind the mirror. A concave mirror produces a virtual image if the object is located between the mirror and the focal point. This situation is shown in the ray diagram in Figure 14. You draw two rays to locate the image of a point on an object. As before, you draw ray 1 parallel to the principal axis and then reflected through the focal point. Ray 2 is drawn as a line from the point on the object to the mirror, along a line defined by the focal point and the point on the object. At the mirror, ray 2 is reflected parallel to the principal axis. Note in Figure 14 that ray 1 and ray 2 diverge as they leave the mirror, so there cannot be a real image. However, sight lines extended behind the mirror converge, showing that a virtual image forms behind the mirror. From the position of the point of convergence, you can see that the image is upright and larger than the object.

Snell's Law of Refraction René Descartes and Willebrord Snell first studied refraction in the seventeenth century by shining a narrow beam of light onto a transparent medium, such as the glass shown in Figure 19. They measured two angles-the angle of incidence and the angle of refraction. The angle of incidence (8) is the angle at which the light ray strikes the surface. The angle of refraction (6.) is the angle at which the transmitted light leaves the surface. Both angles are measured with respect to the normal. Index of refraction Snell found that when light passes from air into a transparent medium, the sines of the angles are related. This index of refraction (n) determines the angle of refraction of light as it crosses the boundary between two mediums. Properties of the mediums light is traveling through determine indices of refraction. Values of n for several mediums are listed in Table 2.