Optics homework help

1.  is not equal to the angle of incidence
1. Parallel rays of light strikes a convex lens. Which of the following diagrams shows what happens to the rays when they strike the lens?
1. An object of height 10 cm is placed 50 cm in front of a bi-convex lens with a focal length of 20 cm. Which of the following is true about the image?
I) The image is virtual
II) The image is situated on the opposite side as the object
III) The image is inverted
A) I only
B) I and II only
C) II and III only
D) II only
E) III only
1. An object of height 5 cm is placed 25 cm in front of a bi-convex lens with a focal length of 10 cm. What is the height of the image?
A) 2.5 cm
B) 12.5 cm
C) 6.8 cm
D) 3.4 cm
E) 7.4 cm
1. An optical fiber is made up of a core of refractive index 1.6 and a cladding of refractive index 1.5. What is the maximum angle that the light rays can make with the axis of the optical fiber so that light is totally reflected inside the optical fiber?
A) 10°
B) 15°
C) 20°
D) 70°
E) 90°
1. For an object in front of a plane mirror, which of the following about its images is(are) true?
I) The image is real
II) The image is upright
III) The height of the image is twice the image of the object
A) I, II and III
B) I and II only
C) II only
D) I and III only
E) None