Optics Review PDF

Optics Review Key Topics Visible Light Mirrors ○ Ray Diagrams ○ Formula Refraction Lenses ○ Ray Diagrams ○ Formula The Eye ○ Parts and diagram ○ Problems Plane Mirror Plane Mirror Image Characteristics :Size of Image (Same): Images are the same size as...

Optics Review Key Topics Visible Light Mirrors ○ Ray Diagrams ○ Formula Refraction Lenses ○ Ray Diagrams ○ Formula The Eye ○ Parts and diagram ○ Problems Plane Mirror Plane Mirror Image Characteristics :Size of Image (Same): Images are the same size as the original object. Attitude of Image (Upright): Images have the same vertical orientation of the original object. Location / Distance of Image (Same): Images are the same distance from the plane mirror as the original object. Type of Images (Virtual): Images are formed in locations where light does not actually reach, they appear “behind” the mirror. Convex Mirror Question A convex mirror has a focal length of 0.9 m. An object with a height of 0.40 m is 2.5 m from the mirror. a. Calculate the image distance. b. Calculate the image height. Refraction Medium: Another word for material Incident Ray : The incoming light ray, in medium 1 Refracted Ray :The outgoing light ray in medium 2 Normal : The line used as a reference point. It is drawn where the incident ray hits the new medium, perpendicular to its surface. Angle of Incidence: The angle between the incident ray and the normal. Angle of refraction: The angle between the refracted ray and the normal. Refraction When light enters a medium that is MORE When light enters a medium that is LESS optically dense then the starting medium (eg. Air optically dense then the starting medium (eg. to water) the light will slow down and as a result Water to air) the light will speed up and as a will bend towards the normal. result will bend away from the normal Refraction Calculations nmedium = c v Example 1: The speed of light in sodium chloride (table salt) is 1.96 x 108 m/s. Calculate the index of refraction for sodium chloride. Example 2: Calculate the speed of light in diamond if the index of refraction of diamond is 2.42. Types of lenses There are 2 general types of lenses: Ray diagrams for convex lenses 2F’ F’ F 2F SALT Ray diagrams for concave lenses 2F F F’ 2F’ SALT * Sign rules for lens calculations +f the lens is a convex lens (converging lens). -f the lens is a concave lens (diverging lens). +di the image is real and located on opposite side of the lens. -di the image is virtual and located on object's side of the lens. +hi the image is an upright image (and therefore, also virtual). -hi the image an inverted image (and therefore, also real).  Parts of the Human Eye Cornea (clear covering) Iris Sclera (coloured disc) Vitreous Humour Ciliary Pupil Sclera Muscle Cornea Optic Nerve Pupil Fovea Lens Retina Iris Path of Light into the Eye Cornea – Transparent, outer layer of eye. – Refracts light towards pupil. Pupil – Black hole in the iris. – Allows light to pass through to the lens. Iris – Circular band of muscle and pigment. – Controls the size of the centre hole (contracts or dilates the pupil). The eye Lens – Transparent, flexible, crystalline convex lens behind pupil. – Refracts and focuses (converges) light. Ciliary Muscle – Muscle fibres from sclera to lens. – Controls shape of lens to allow lens to focus. The Eye Retina – Inner lining of light-sensitive cells that covers back of eye; surrounded by network of nerves. – Detects light (of the real image), and transmits this as a signal to the optic nerve. – Photoreceptive cells in the retina are referred to either as “rods” or “cones”. – Rod cells are more sensitive to light (therefore details). – Cone cells detect either red, green, or blue wavelengths of light. (therefore colour vision).  Myopia Light refracts through the lens Image falls SHORT of the retina Vision is corrected using a diverging (concave) lens Light diverges before hitting the natural lens of the eye Hyperopia Light refracts through the lens Image forms BEYOND the retina Vision is corrected using a converging (convex) lens Light converges before hitting the natural lens of the eye