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Mirrors and Lenses
Science 8 - Mirrors and Lenses
Term | Definition |
---|---|
Plane mirror | Regular, flat mirrors |
Incident Ray | Ray of light that travels toward a reflecting surface |
Angle of Incidence | The angel between the incident ray and the normal |
Normal | The line drawn from the point of incidence at 90 degrees to the surface of the optical device |
Reflected Ray | Ray of light that bounces off a reflecting surfaces |
Angle of Reflection | the angel between the reflected ray and the normal |
Point of incidence | The spot where the incident ray strikes the reflecting surface |
Specular reflection | The reflection of light off a smooth, shiny surface. Reflects a clear image. |
Laws of reflection (2) | 1. The angle of incidence equals the angle of reflection 2. The incident ray, normal and reflected ray all lie in the same plane. |
Diffuse Reflection | When light hits an irregular surface - you see a blurred image. |
Real image | Can be placed on a screen |
Virtual image | Cannot be placed on a screen - can only been seen looking through an optical device (like a lens) |
Optical Device | Produces an image of an object |
What four characteristics are used to stud and compare images? | 1. Size (smaller, large or same size as the object viewed), 2. Attitude (upright or upside down), 3. Location (Several choices such as on the side of the lens, opposite the object), 4. Type (real or virtual image) |
Convex Mirror | The mirror curves outwards towards the object (like the back of a spoon) - allows you to see more area; good for surveillance |
Concave Mirror | The mirror curves inwards (caves in) (like the inside of a spoon) - allows you to see things up close |
Virtual or Real: Plane Mirror | Virtual |
Virtual or Real: Concave Mirror (Object closer than principal focus) | Virtual |
Virtual or Real: Convex Mirror | Virtual |
Virtual or Real: Concave Mirror (Object beyond principal focus) | Real |
Refraction | The bending of light as it travels from one material into another |
Angle of Refraction | The angle between the refracted ray and the normal |
Refracted Ray | The ray of light that changes direction as it passes from one material into another |
Lens | A curved, transparent device that causes light to refract as it passes through |
Principal Focus | the position where parallel light rays come together |
Focal Length | The distance from the principal focus to the centre of the lens |
Name three devices that use at least one lens | Glasses, microscope, telescope, camera, contacts, binoculars |
Optical telescopes | collect visible light |
Refracting telescopes | Uses a series of convex lenses |
Refleccting telescopes | Uses mirrors and lenses (may be very large) |
Radio telescopes | Collect radio waves uses large concave antenna systems usually have several radio telescopes in one area Uses a computer to create th eimage |
X-Rays and Gamma Ray Telescopes | Collect short wave length radiation Uses computers to view the image |