Images in Curved Mirrors SNC2D

Types of Curved Mirrors To make a curved mirror, you make part of the surface of the sphere reflective. There are 2 types: 1) Concave (Converging) Mirror- shaped like part of the surface of a sphere in which the inner surface is reflective. 2) Convex (Diverging) Mirror- shaped like part of the surface of a sphere in which the outer surface is reflective.

Concave Mirror Terminology Principal Axis- the line through the centre of curvature to the midpoint of the mirror. Vertex- the point where the principal axis meets the mirror. Labelled V.

Focus- the point at which light rays parallel to the principal axis converge (meet at a common point) when they are reflected off a concave mirror. Labelled F. Centre of Curvature- the centre of the sphere whose surface has been used to make the mirror. Labelled C.

Locating Images in Concave Mirrors To determine the image of an object in front of a concave mirror you need to draw at least two incident rays from the top of the object. RULES: 1) A light ray parallel to the principal axis is reflected through the focus. 2) A light ray through the centre of curvature is reflected back onto itself. 3) A ray through the focus will reflect parallel to the principal axis. 4) A ray aimed at the vertex will follow the law of reflection.

Do you remember what a REAL image is? If you place a luminous object beyond C, you can locate the image by moving a paper screen back and forth in front of the mirror. A Real Image is an image that can be seen on a paper screen as a result of light rays actually arriving at the image location.

Case 1: Object located beyond Centre of Curvature When an object is located beyond C, the image will always be located between C and the Focus. The image will be inverted. The image is reduced in size. The image is real.

Case 2: The object is located at the Centre of Curvature When an object is located at C, the image will also be located at C. The image is inverted. The image is the same size. The image is real.

Case 3: The object is located between C & F When an object is located between C & F, the image will be located beyond C. The image is inverted. The image is larger. The image is real.

Case 4: The object is located at F When the object is located at F, there is no image formed. WHY? Light rays from the same point do not converge or diverge. Reflected rays are parallel and do not form images.

Case 5: Object located in Front of F When an object is located beyond F, the image will always be located somewhere on the opposite side of the mirror. The image is upright. The object is larger. The image is virtual. This is because the rays diverge and our brain extrapolates the rays backwards to where they appear to originate.

Summary: Imaging properties of a Converging Mirror OBJECT IMAGE Location Size Attitude Type Beyond C Smaller Inverted Between C & F Real At C Same Larger At F No Clear Image Inside F Upright Behind Mirror Virtual