180° phase change Thin Film Interference (just for your information) Thin Film Interference (just for your information) Ray undergoes a phase change on reflection. Ray has a phase change due to the path difference.
PHYS 104 LECTURE PHYS 104 LECTURE Problems Problems Electromagnetic Waves and Electromagnetic Waves and Optics Optics Chapter 24-25 Chapter 24-25
Mirrors and Lenses • The development of mirrors and lenses aided the progress of science. • It led to the microscopes and telescopes. – Allowed the study of objects from microbes to distance planets • Images can be formed by reflection from mirrors. • Images can be formed by refraction through lenses. • Will look at the formation of these images • Will continue to use the ray approximation Introduction
Notation for Mirrors and Lenses • The object distance is the distance from the object to the mirror or lens. – Denoted by p • The image distance is the distance from the image to the mirror or lens. – Images are formed at the point where rays actually intersect or appear to originate. – Denoted by q • The lateral magnification of the mirror or lens is the ratio of the image height to the object height. – Denoted by M Section 23.1
Types of Images • Images are classified as real or virtual. • Real images are formed at the point the rays of light actually intersect. – Real images can be displayed on screens. • Virtual images are formed at the point the rays of light appear to originate. – The light appears to diverge from that point. – Virtual images cannot be displayed on screens. Section 23.1
More About Images • To find where an image is formed, it is always necessary to follow at least two rays of light as they reflect from the mirror. Section 23.1
Magnification • The lateral magnification is defined as • Magnification doesn’t always mean enlargement. – The image can be smaller than the object. Section 23.1
Flat Mirror • Properties of the image can be determined by geometry. • One ray starts at P, follows path PQ and reflects back on itself. • A second ray follows path PR and reflects according to the Law of Reflection. Section 23.1
Properties of the Image Formed by a Flat Mirror • The image is as far behind the mirror as the object is in front. – p = |q| • The image is unmagnified. – The image height is the same as the object height. – h’ = h and M = 1 Section 23.1
More Image Properties – Flat Mirror • The image is virtual. • The image is upright. – It has the same orientation as the object. • There is an apparent left-right reversal in the image. Section 23.1
Application – Day and Night Settings on Auto Mirrors • With the daytime setting, the bright beam of reflected light is directed into the driver’s eyes. • With the nighttime setting, the dim beam of reflected light is directed into the driver’s eyes, while the bright beam goes elsewhere. Section 23.1
Spherical Mirrors • A spherical mirror has the shape of a segment of a sphere.
- Spring '20
- Light, Total internal reflection, Geometrical optics, rays