Answer: At 15 cm (in front).
- A At 15 cm (behind mirror)
- B At 15 cm (in front)
- C At 30 cm (in front)
- D At infinity
Correct answer: B. At 15 cm (in front)
Explanation: 1/v + 1/u = 1/f. 1/v + 1/(-30) = 1/(-10). 1/v = -1/10 + 1/30 = -3/30 + 1/30 = -2/30. v = -15 cm. Real image 15 cm in front.
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.