Answer: 4 D.
- A 0.25 D
- B 2.5 D
- C 4 D
- D 40 D
Correct answer: C. 4 D
Explanation: P = 1/f (in metres) = 1/0.25 = 4 D.
Concave mirror ray construction: a ray parallel to the axis reflects through F, and a ray through F reflects parallel, locating the inverted real image. Image: Maxmath12, CC0, via Wikimedia Commons.
Concept context
Reflection, refraction, lenses, mirrors, total internal reflection.