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Solution Steps and Grading Key for Part II: Ray Diagram (10P) 1P: Draw optical axis, mirror principal plane, H, and correctly placed object as arrow to the left of the mirror, with all 3 elements properly labeled. 1P: Correctly identify and label incoming side of mirror, to the right of mirror. Reasoning: i) object is virtual  by sign convention, object is located not on incoming side ii) object is to the left of lens  to the left of lens is not the incoming side iii)  incoming side is to the right of the lens 1P: Correctly identify and label outgoing side, to the right of the mirror: Reasoning: i) The device is a mirror which reflects rays back to the same side they came from. ii) Outgoing side is the same as incoming side: to the right of mirror. 1P: Correctly place focal points F and F’: coincident to the left of the mirror, between mirror and object, on the optical axis. Label F=F’. Reasoning: i) mirror is divergent, i.e., has negative focal length f<0. ii)  by sign convention, F is not on “in” and F’ is not on “out” side, i.e., F and F’ are both to the left of mirror. iii) F and F’ are at both at a distance |f| from mirror, to the left  F and F’ coincide. iv) absolute object distance from mirror, |d|, is greater than absolute focal length, |f| v)  F, F’ are located between object and mirror. 2P: Correctly draw one of the three principal ray pairs (see drawing Examples 1, 2): Either: F-­‐F’-­‐ray Or: P-­‐P’-­‐ray Or: C-­‐C’-­‐ray 2P: Correctly draw a second principal ray pair (see drawing Examples 1, 2): Either: P-­‐P’-­‐ray Or: C-­‐C’-­‐ray Or: F-­‐F’-­‐ray Note: For a mirror (unlike a lens!) the C-­‐ray and C’-­‐ray are two distinct lines, each intersecting the optical axis at the same angle, but one from above, the other from below. So, the C’-­‐ray must be constructed from the C-­‐ray, by reflecting the C-­‐ray at the optical axis -­‐-­‐ unlike a lens, where the C-­‐ray is simply continued straight trough the lens to get the C’-­‐ray. 1P: Correctly draw image at intersection of two outgoing principal rays as arrow to the left of mirror, arrow oriented opposite to object arrow, i.e., inverted relative to object (see drawing Examples 1, 2). Note: Depending on choice of object position, the image may be (i) closer the mirror than the object, i.e., |d’| < |d|; or (ii) further away, i.e., |d’| > |d|. Case (i) arises if the object position is chosen such that |d|>2|f|; case (ii) arises if |d|<2|f|. 1P: State: image is virtual. Reasoning: i) image is formed to the left of the mirror  image is not on outgoing side ii)  by sign convention: image is virtual and d’<0