Answer: Real, at 60 cm other side.
- A Virtual, at 60 cm same side
- B Real, at 60 cm other side
- C Real, at 12 cm other side
- D Virtual, at 12 cm same side
Correct answer: B. Real, at 60 cm other side
Explanation: 1/v - 1/u = 1/f. 1/v - 1/(-20) = 1/15. 1/v = 1/15 - 1/20 = 4/60 - 3/60 = 1/60. v = 60 cm. Real image opposite side.
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.