Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Refraction of Light n Index of Refraction: Wavelength of light in a material: c v (n ≥ 1) n vac n Because light travels at different velocities in different materials, light “bends” or refracts at the interface between two materials. Snell’s Law: n1 sin 1 n2 sin 2 - for light traveling from material 1 to material 2 - if n1 < n2, the light is bent “toward” the normal (θ2 < θ1) - if n1 > n2, the light is bent “away” the normal (θ2 > θ1) n d d 2 n1 n Critical Angle: (n1 > n2) sin c 2 n1 - Total Internal Reflection: for angles at the critical angle and bigger, no light is transmitted into material 2; the light ray just skims along the interface between the two materials. Apparent depth: The index of refraction of a material depends slightly on the wavelength of light. This leads to dispersion – the spreading of light into its color components. Examples of dispersion of light: prisms and rainbows. Lenses To understand thin lenses (and mirrors) and the images they form, we trace the paths of light rays from the object to the lens (or mirror) and then on to where the image is formed. An image is formed where the light rays all “intersect”. For a real image, the light rays really do intersect. For an imaginary image, the light rays do not actually intersect because they are diverging. We trace the actual light rays back through the lens to see where they appear to come from – this is the location of the imaginary image. In this class, to minimize confusion, we always work from left to right. So a real object is to the left of the lens. In real life, of course light can go left to right or right to left through a lens. Converging Lens Object Placement Image Type Image Size Beyond 2F Between 2F & F Real Real Reduced Enlarged Image Orientation Inverted Inverted Between F and Lens Virtual Enlarged Upright Example Camera Film projector Magnifying glass Diverging Lens Object Placement Anywhere Image Location/Type Virtual Image Size Reduced Thin Lens Equation: 1 1 1 do di f Magnification Equation: m Image Orientation Upright hi d i ho do Sign Conventions - Focal Length converging lens: f=+ diverging lens: f=- Object Distance object to left of the lens (real object): do = + “object” (image from first lens) to right of 2nd lens (virtual object): - Image Distance image formed to right of lens (real image): di = + image formed to left of lens (virtual image): di = - Magnification image is upright: m = + image is inverted: m = Compound lens equation (lenses touching each other): do = - 1 1 1 f1 f 2 f Lenses in combination but not touching: with a multiple lens system, you apply the thin lens equation to each lens separately to find the location of the final image. The image from the first lens serves as the object for the second lens.