Transcript Mirrors
Recall: Light must reflect off of an object before it can be used to see the object. Light wave A plane mirror generates a virtual image (the image of the object that is being reflected) that is upright and appears to be the same distance away from the surface as the object is. A flat mirror is called a plane mirror. Concave Mirrors: The reflecting surface of the mirror is curved inward (mnemonic: the mirror is caved in) • Concave mirrors form real images because light rays pass through the image position. • A real image can be projected onto a piece of paper. • The focal point is the point through which all parallel incoming light rays are reflected. • The distance along the optical axis to the focal point is called the focal length. The image that is formed by a concave mirror depends upon where the object is positioned. If the object is positioned at a distance greater than the focal length, the the object will be: Smaller and inverted The image that is formed by a concave mirror depends upon where the object is positioned. If the object is positioned inside of the focal length, the image will be: • Virtual • Upright • Larger Convex Mirrors: The reflecting surface of the mirror is curved outward. Images formed by convex mirrors are: • Upright • Smaller than actual object Example: Fish-eye mirrors for surveillance. Lenses: A lens is any material that causes light to refract as it passes through it. The size and orientation of the image depends upon: • The shape of the lens (concave vs. convex) • The position of the object in comparison to the focal point A convex lens, like a convex mirror, has outwardly curved surfaces When the image is more than two focal lengths away from the lens, the image is: • Real • Inverted • smaller If the image is between one and two focal lengths away from the lens, the image is: • Real • Inverted • LARGER When the object is less than one focal length away from the lens, the image is: • Virtual • Upright • LARGER A concave lens always produces images that are: • Virtual • Upright • smaller