Geometrical optics Flashcards
Optics
The study of light
Light is a particle
Corpuscular theory of light. Pre newton are (before 1600). Explains emission and absorption of light. geometrical optics.
Light is a wave
Wave theory. propagation of light (how light moves in space). during newton era (1600). physical optics.
Light has dual nature
Light behaves as a particle and a wave. post newton (1930).
Rectilinear propagation
Light travels in a straight line.
Law of reflection
The incident angle is equal to the reflected angle.
The incident ray, the normal line and the reflected ray are in the same plane.
The plane mirror properties
- The image is upright in respect to the object
- The image is the same size as the object
- The image distance is the same as the distance of the object.
- The image is virtual in respect to the object.
- The image is left right reversed.
Concave mirror
The inside surface of the spherical mirror is polished.
Convex mirror
The outside surface of the spherical mirror is polished.
Principle Axis
A straight line drawn through the center and midpoint of the mirror.
Paraxial rays
Rays that lay close to the principle axis
Spherical abberation
A spherical mirror does not bring all the parallel rays to a single point. results in a blurry image.
Refraction
The change in direction of light when it travels from one medium to another of different optical density and strikes the separation at an incident angle larger than 0 degrees.
Laws of refraction
The incident ray, the normal line in the incident point and the refracted ray are all in the same plane.
Snell’s law (second law of refraction).
The ratio of sin incident angle to sin refracted angle is constant for any two given media in contact.
When light travels from a material with one index of refraction to a material with a different index of refraction, the angle of incidence is related to the angle of refraction.
Index of refraction
The ratio of the speed of light in vacuum to the speed of light in the material.
Critical angle
When light travels from a more dense medium to a less dense medium and the refracted angle is equal to 90 degrees then the incident angle in the more dense medium is called the critical angle.
Total internal reflection
When light travels from a more dense medium to a less dense medium and the incident angle becomes greater than the critical angle the light is no longer refracted at the separation but it is reflected back into the medium.
Two conditions for total internal reflection
- The light ray must originate from a more dense medium to a less dense medium.
- The incident angle must exceed the critical angle.
Converging lens (convex lens)
Paraxial rays that are parallel to the principle axis converge to the focal point
Diverging Lens (concave lens)
Paraxial rays that are parallel to the principle axis appear to originate from the focal point.
Nearsightedness (Myopia)
The person can see near objects clearer than far or distant objects
Diverging lens (Myopia)
creates an image of the distant object at the far point of the nearsighted eye.
The near point
The point nearest the eye at which an object can be placed and still produce a sharp image on the retina.
Far point of nearsightedness
The location of the furthest object on which the fully relaxed eye can focus
Farsightedness (hyperopia)
Able to focus on far objects and not on near objects
Converging lens (Hyperopia)
creates an image of the close object
