Answer: 15 D.
- A 10 D
- B 15 D
- C 30 D
- D 2 D
Correct answer: B. 15 D
Explanation: P = P<sub>1</sub> + P<sub>2</sub> = 100/10 + 100/20 = 10 + 5 = 15 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.