Image Formation and Ray Diagrams Mirrors and Lenses

• The physical object in front of the mirror is called the object while the picture we see in the mirror is called the image.
• Real Images: occur when light rays actually intersect or converge making them appear inverted or upside down.
• Virtual Images: occur when light rays diverge which form an upright image.
• Plane mirrors consist of a flat, two-dimensional surface that reflects the light coming from or reflecting off another object.
• Law of Plane Mirrors: states that the image is always the same distance behind the mirror as the object is in front of the mirror.
• The image of a plane mirror is virtual, upright, and same size.
• Center of Curvature: the center of the circle in which the mirror represents a small arc
• Focus: the point where parallel light rays converge
• Vertex: the point where the mirror crosses the principal axis
• Principal Axis: an imaginary line passing through the vertex of the lens perpendicular to its curved side
• Focal Length: the distance from the focus to the vertex of the mirror
• Radius of Curvature: the distance from the curvature to the vertex of the mirror
• Spherical Mirrors: a spherical surface that is cut then polished such that light can be focused to converge to a point image
• Convex Mirrors: curve outwards
• Convex Mirrors always produce a virtual, upright, and smaller image.
• Convex Mirrors Examples:

  • passenger-side wing mirrors
• Concave Mirrors: are able to make rays of light converge to a focus; curve inwards.
• Concave Mirrors Examples:

  • shaving mirrors
  • makeup mirrors
• Concave mirrors magnify objects that are placed close to them
• Ray Diagram: traces the path that light takes in order for an individual to view a point on the image of an object
• Rules in Ray Diagramming:

  • Any ray through the focal point will reflect parallel to the principle axis
  • Any ray parallel to the principle axis will reflect sp that it passes through the focal point
  • Any ray that passes through the center will reflect back through the center
• Real Images: can be projected onto a screen or film, formed by convex lenses and concave mirrors
• Virtual Images: cannot be projected onto a screen or film, formed by concave lenses and convex mirrors
• Principal Ray: ray that leaves a point on an object facing the mirror parallel to the principal axis
• Focal Ray: ray that leaves the same point on the object and immediately passes through the focal point, hitting the mirror and reflecting parallel to the principal axis
• Chief Ray: ray that leaves the same point on the object and passes through the center of curvature
• The mirror equation expresses the quantitative relationship among the object distance, image distance, and focal length.
• The magnification equation relates he ratio of the image distance and the object distance to the radio of the image height and object height.
• The image of an object beyond the center of curvature will appear between the focus and the center of curvature as real, inverted, and smaller
• The image of an object at the center of curvature will appear on the center of curvature as real, inverted, and same size
• The image of an object between the center of curvature and focal point will appear beyond the center of curvature as real, inverted, and larger
• The image of an object at the focal point will not create an image
• The image of an object between the mirror and focal point will appear behind the mirror as virtual, upright, and larger
• The image of an object at affinity will appear at the focus as real, inverted, and smaller
• A lens is a shaped transparent material that refracts light to create an image.
• Converging Lens or Convex Lens: lens that is thicker in the middle
• Diverging Lens or Concave Lens: lens that is thinner in the middle than at the edges
• Principal Axis: line joining the centers of curvatures of its surface
• Principal Focus: point where they converge
• The image created by a concave lens or diverging lens is always virtual, upright, and smaller