EQ Sheet 3

# EQ Sheet 3 - Dual Nature of Light photons are both...

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The angle of refraction ( θ2 ) depends upon properties of medium & angle of incidence The angle of reflection ( θ1’ ) is equal to the angle of incidence (θ1): ( θ1= θ1’ ) Light Refracts into material w/t LOWER SPEED (higher index of refraction (n) Light Refracts into material w/t HIGHER SPEED (lower index of refract ion (n) Angle of refraction   ( 2) is θ   LESS  THAN angle  of  incidence  ( 1)  θ Angle of refraction   ( 2) is θ   LESS  THAN angle  of  incidence  ( 1)  θ Light ray bends TOW ARDS the NORM AL Light ray bends AW AY from the Ex. Light travels from AIR (n=1) into GLASS (n=1.52-1.66 depend. on type) Ex. Light travels from GLASS (n=1.5) into AIR (n=1) AS wavespeed (v) DECREASES index of refraction (n) INCREASES AS wavespeed (v) INCREASES index of refraction (n) DECREASES Reduction in wavelength when light travels from index of refrac. Increase wavelength of refrac. Dual Nature of Light: photons are both particles & waves Refraction Details: Index of refraction (n) = speed of light in a vacuum speed o f light in a medium (v) n=3X10 8 m/s Light is refracted because the speed of light is different as it passes from one medium to another Speed of light (v) = (freq. (f)) X (wave length (λ)) n=c/v v=fλ n1sin  1 =  θ n2sin  2 θ RAINBOWS: Ray of light strikes drop of water in atmosphere. Reflect. & Refrac. both occur1st undergoes refraction at front of drop. (VIOLET – deviates most) (RED – deviates least) Reflection & Refraction Fiber optics = work by total internal reflection. Used for medical diagnosis & correction of med probs and used in telecommunicatio n 1.laser beam with vacuum wavelength of  _nm is  incident from air (n=1) into a block of Lucite. Find  a)  speed, b) frequency and c)wavelength of light in Lucite  ( 1=°  2=°) θ θ Step 1: solve for n2 n2 =n1 sinθ1 /sinθ2 Step 2: find speed (v2) a) v2 = c / n2 Step 3: find freq (f) b) f = c / λ o Step 4: find wavelength (λ2) c) λ2 = λ o / n2 Diffraction – when light spreads out (for mirrors & lenses we think of light as a ray and ignore diffraction) Mirrors and Lenses The object distance is the distance from the object to the mirror or lens (Denoted by p) The image distance is the distance from the image to the mirror or lens. Images are formed at the point where rays actually intersect or appear to originate (Denoted by q) A real image is one in which light actually passes through the image point. (Real images can be displayed on screens (movies)) A virtual image is one in which the light does not pass through the image point. The light appears to diverge from that point (Virtual images cannot be displayed on screens) Lateral Magnification: doesn’t always mean enlargement (image can be smaller than object) {AE723A9 -5E 5-C74E-9E19-98ED2F12B 95} Flat Mirrors Image as far behind mirror as object is in front of it Image is unmagnified (image height (h’) = object height (h)) and M=1

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EQ Sheet 3 - Dual Nature of Light photons are both...

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