Test Corrections Due Tuesday April 26 th Corrections

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Test Corrections • • • Due Tuesday, April 26 th Corrections must be done

Test Corrections • • • Due Tuesday, April 26 th Corrections must be done in a different ink color Lots of 4’s for effort – doesn’t mean answer is right! • • • Check solutions Show formula, explain your conclusions Mistake in my solutions • • No points deducted for effort One person did it correctly and got 1 point extra credit! General Physics 2 Geometric Optics 1

Geometric Optics • Ray Model • • assume light travels in straight line uses

Geometric Optics • Ray Model • • assume light travels in straight line uses rays to understand predict reflection & refraction General Physics 2 Geometric Optics 2

Reflection • Law of reflection • • the angle of incidence equals angle of

Reflection • Law of reflection • • the angle of incidence equals angle of reflection angles are measured from normal General Physics 2 Geometric Optics 3

Reflection Diffuse reflection General Physics 2 Specular reflection Geometric Optics 4

Reflection Diffuse reflection General Physics 2 Specular reflection Geometric Optics 4

Plane Mirrors General Physics 2 Geometric Optics 5

Plane Mirrors General Physics 2 Geometric Optics 5

Think-Pair-Share • How large a mirror do you need to see your whole body?

Think-Pair-Share • How large a mirror do you need to see your whole body? General Physics 2 Geometric Optics 6

Spherical Mirrors By using ray tracing and the law of reflection, you can figure

Spherical Mirrors By using ray tracing and the law of reflection, you can figure out where the incoming rays are reflected. General Physics 2 Geometric Optics 7

Focal Point & Focal Length • Parallel rays striking a concave mirror come together

Focal Point & Focal Length • Parallel rays striking a concave mirror come together at focal point f = r/2 r = radius of sphere f = focal length General Physics 2 Geometric Optics 8

Refraction • index of refraction, n, where c = speed of light in a

Refraction • index of refraction, n, where c = speed of light in a vacuum and v = speed of light in that medium • • • nair = 1 nglass = 1. 5 Snell’s Law General Physics 2 Geometric Optics 9

Indices of Refraction General Physics 2 Geometric Optics 10

Indices of Refraction General Physics 2 Geometric Optics 10

Total Internal Reflection • • Incident angle where refracted angle ( 2) is 90

Total Internal Reflection • • Incident angle where refracted angle ( 2) is 90 is the critical angle at incident angles greater than critical angle, light is totally internally reflected important for fiber optic technology (endoscope) General Physics 2 Geometric Optics 11

Thin Lenses General Physics 2 Geometric Optics 12

Thin Lenses General Physics 2 Geometric Optics 12

Focal Length, Focal Plane and Power • • f = focal length Power •

Focal Length, Focal Plane and Power • • f = focal length Power • • inverse of focal length P = 1/f measured in diopter (D) 1 D = 1 m-1 General Physics 2 Geometric Optics 13

Ray Tracing General Physics 2 Geometric Optics 14

Ray Tracing General Physics 2 Geometric Optics 14

Thin Lens Equation Magnification Thin Lens Equation General Physics 2 Geometric Optics 15

Thin Lens Equation Magnification Thin Lens Equation General Physics 2 Geometric Optics 15

Sign Conventions • focal length • • • object distance • • • positive

Sign Conventions • focal length • • • object distance • • • positive if the object is on the side of the lens from which the light is coming (this is usually the case) otherwise, it is negative (virtual object). image distance • • • positive for converging lenses negative for diverging lenses positive if the image is on the opposite side of lens from where light is coming positive for real images, negative for virtual images image height • • positive if image is upright relative to object, negative for inverted images h 0 is always positive General Physics 2 Geometric Optics 16

Combination of Lenses • When adding two or more lenses in series, the focal

Combination of Lenses • When adding two or more lenses in series, the focal length of the combined lenses, f, is: General Physics 2 Geometric Optics 17

Combining Lenses • Measure the focal length of the two double-convex lenses individually. Combine

Combining Lenses • Measure the focal length of the two double-convex lenses individually. Combine the lenses together and measure the combined focal length. Calculate the combined focal length using the equation. • Calculate the percent error of your measured value. • • General Physics 2 Geometric Optics 18

Activity • Handouts with practice problems • Optics Worksheet 1 and 2 General Physics

Activity • Handouts with practice problems • Optics Worksheet 1 and 2 General Physics 2 Geometric Optics 19