Geometric Optics

 Spherical Mirrors

 Solutions

 Q1: Estimate by eye the radius of curvature for your mirror. For mirror R =1 m For spoon R =5 cm Q2: Hold your concave mirror at arms length and describe the image of yourself in the mirror.  Is it upright or inverted?  What is the approximate magnification? Is the image virtual or real?   Image is inverted, smaller and real. Q3: Move a finger along the principle axis towards the mirror vertex and describe how its image changes. Does the image change magnification and how? Does it disappear or invert and if so where? What is magnification when the fringe is touching the spoon?  At distances greater than R image is inverted and smaller. At distances between f and R image is inverted and larger. At distances around R image will apparently disappear. At distances less than R image will be erect and larger. At the mirrors surface the magnification will be 1:1. Q4: When your finger is at a distance R from the mirror it appears to have an  M = -1.0, what are R and f for this mirror? For mirror R= 1 m For spoon R =5 cm f = R Q5: Hold your convex mirror at arms length and describe the image of yourself in the mirror.  Is it upright or inverted?  Approximately what magnification? Is the image virtual or real?   Image will be erect, smaller and virtual. Q6: Now move a finger along the principal axis towards the mirror vertex and describe how its image changes.  Does the image change magnification and how?  Does it disappear or invert and if so where? What is the maximum magnification?  Image remains erect and smaller at any distance form mirror. Magnification decreases with distance. Maximum magnification is 1:1 at mirror's surface. Q7: Car side Mirrors often have "CAUTION: OBJECTS IN MIRROR ARE CLOSER THAN THEY APPEAR" etched on them (remember the movie Jurassic Park ?)  Explain why.  Car side mirrors are convex mirrors. Images in convex mirrors are always smaller than the object. We perceive this decrease in size as an exaggeration of distance to the object.

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