12. A spherical mirror with reflecting surface curved inwards is called
a. concave mirror
b. curved mirror C. convex mirror d. none of the above
13. The distance from the focal point to the vertex is called
a. center of curvature
b. focal point
c. focal length d. vertex
14. Which lens is used to magnify objects and refract light? This type of lens is curved outward.
a. concave lens
b. convex lens c. parabolic lens d. plane lens
15. Which describes a concave lens?
a. more transparent in the middle
b. thinner in the middle than on the edges
c. thinner on the edges than in the middle
d. triangular in shape.​