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Mathematical determination the mirror image. MATHEMATICAL DETERMINATION OF DIAGRAM VALUES. VARIABLES. Mathematical Solution. h means height d means distance f means length between vertex and focal point i means image o means object. MAGNIFICATION. Magnification equations.
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Mathematical Solution h means height d means distance f means length between vertex and focal point i means image o means object
Magnification equations M = hi / ho M = -di / do
Combine the equations M = hi / ho =-di / do hi / ho
Image is inverted (upside down on other side of PA)
When are other values are negative Values are negative if : Distance is virtual, across the other side of the mirror from the object The focal length for a convex mirror, since it is on the other side of the mirror
Mirror equation 1/f = 1/ di + 1/do
Mirror equation Proof
Both equations Proof through geometry Based on distances heights found in diagrams Approximate value, not exact
Radius of curvature • Radius of curvature = distance from center point to vertex r = twice the focal length (f)
When solving these problems • Make sure all units are the same, but do not worry if it is not in the standard metric units. • Watch for negative values in given units!!!
Example problem A 3.00 cm tall object is 20.0 cm from a 16.0 cm radius concave mirror. A. Determine the image position B. Determine the image height
About units • If all units are the same, do NOT convert. • Leave in cm, mm, m…
Answer to part A • Radius of curvature = twice the focal length = 2f • 16 = 2f means f = 8 cm • The do = 20cm (given) • Use mirror equation: 1/8 = 1/20 + 1/di • Solve di = 13.3 cm, means image is real oand on same side as object
Answer to part B • Ho = 3.0 • 3/Hi = -13.3 / 20 • Hi = -4.51 large and inverted than object
Another example problem • An object 2.0 cm high is 30.0 cm from a concave mirror. The radius of curvature of the mirror is 20.0 cm. a. What is the location of the image? b. What is the size of image?
3rd example problem • If an object is 2.0 cm in height is 5.0 cm in front of a concave mirror of focal length 10.0 cm. Determine the size and location of the image. • Is image real/virtual and what is the orientation of image?
Homework • In the text book • Pg 469 13-16 • Pg 472 17-21 • Odds should have answers in the back of the book