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 2Geometric Optics1

General Physics 2Geometric Optics2 Ray Model assume light travels in straight line uses rays to understand and predict reflection & refraction

General Physics 2Geometric Optics3 Reflection Law of reflection the angle of incidence equals angle of reflection angles are measured from normal

General Physics 2Geometric Optics4 Reflection Diffuse reflectionSpecular reflection

General Physics 2Geometric Optics5 Plane Mirrors

General Physics 2Geometric Optics6 Think-Pair-Share How large a mirror do you need to see your whole body?

General Physics 2Geometric Optics7 Spherical Mirrors By using ray tracing and the law of reflection, you can figure out where the incoming rays are reflected.

General Physics 2Geometric Optics8 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 2Geometric Optics9 Refraction index of refraction, n, where c = speed of light in a vacuum and v = speed of light in that medium n air = 1 n glass = 1.5 Snell’s Law

General Physics 2Geometric Optics10 Indices of Refraction

General Physics 2Geometric Optics11 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 2Geometric Optics12 Thin Lenses

General Physics 2Geometric Optics13 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 2Geometric Optics14 Ray Tracing

General Physics 2Geometric Optics15 Thin Lens Equation Magnification

General Physics 2Geometric Optics16 Sign Conventions focal length positive for converging lenses negative for diverging lenses 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 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 2Geometric Optics17 Combination of Lenses When adding two or more lenses in series, the focal length of the combined lenses, f, is:

General Physics 2Geometric Optics18 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.

Activity Handouts with practice problems Optics Worksheet 1 and 2 General Physics 2Geometric Optics19