Question

6. (a) The lens in a magnifying glass produces a magnification of +3.0 when held 5.0 cm from an object - in this case a rare coin. (i) (3 pts) What is the focal length of the lens? (ii) (3 pts) How far is the image of the coin from the lens? Is it real or virtual? (b) (4 pts) Identify the optical elements in the dashed boxes in the two diagrams below (i.e. diverging lens, converging lens, convex mirror, concave mirror, or plane mirror); the solid arrow represents the object and the dashed arrow represents the image. To receive full credit, you MUST justify your answer, either by tracing rays between the arrows, or on the basis of the respective orientations, sizes and locations of the arrows. (i) (ii)

Answer 1

60) m = +3 -5.oum - Sim is form convention M 부 u = 3= -5 V--15.0 cm Now I & = // h = -1/15 - 5 = 1/2 - 1/3 = 3 1 - f = 15 - 7.5cm a 6 focal length f= +7.5cm to Image will be isun (vels an) from the lens is positive hence visual image. here m=+3

16 1 Here image is of small size and vertual and opposite side of optical elements so it is convex mirno. say diagram F (7) Here image is of small size and virtual and same side of ophical element. So it is concave lens say diagram