102) Thin Lenses: A drawing is placed 40 cm in front of a thin lens. If a virtual image forms 102) at a distance of 50 cm from the lens, on the same side as the drawing, what is the focal length of the lens? A) 75 cm B) -45 cm C) 90 cm D) +45 cm E) 200 cm 103) Thin Lenses: An object is placed 10 cm from a convex lens with a focal length of magnitude 20 cm. What is the magnification? A) 1.5 B) 0.50 C) 2.0 D) -2.0 103) E) -2.5 104) Thin Lenses: How far from a lens having a focal length of +50 mm must the object be 104) placed if it is to form a virtual image that is 3.0 times the size of the object? A) 33 mm B) 54 mm C) 48 mm D) 42 mm 105) Snell's Law: A beam of light in water (of refractive index of 1.33) enters a glass slab (of 105) refractive index 1.50) at an angle of incidence of 60.0°. What is the angle of refraction in the glass? A) 60.0° B) 39.8° C) 90.0° D) 27.5° E) 50.2° 106) Snell's Law: A beam of light traveling in air strikes a glass slab at an angle of incidence 106) less than 90°. After entering the glass slab, what does the beam of light do? (There could be more than one correct choice.) A) I follows the same path as before it struck the glass. B) It follows the normal to the glass slab. C) It bends closer to the normal at the point of contact. D) It bends away from the normal at the point of contact. E) It slows down. 107) Total Internal Reflection: An optic fiber is made of clear plastic with an index of 107) refraction of 1.50. For what range of angles of incidence with the lateral surface of the fiber will light remain inside the plastic "guide" if it is surrounded by air? A) 41.8° < < 90° B) 40.3° < < 90° C) 38.3° < < 90° D) 21.1° < < 90° E) 23.4° < < 90° 108) Thin Lenses: Starting from very far away, an object is moved closer and closer to a converging lens, eventually reaching the lens. What happens to its image formed by that lens? (There could be more than one correct choice.) A) The image keeps getting larger and larger. B) The image gets farther and farther from the lens. C) The image gets closer and closer to the lens. D) The image eventually changes from real to virtual. E) The image eventually changes from virtual to real. 18 Browsegrades.net 108)