Answer: omega 1 /f 1 + omega 2 /f 2 = 0.
- A f<sub>1</sub> = f<sub>2</sub>
- B omega<sub>1</sub>/f<sub>1</sub> + omega<sub>2</sub>/f<sub>2</sub> = 0
- C omega<sub>1</sub> x f<sub>1</sub> = omega<sub>2</sub> x f<sub>2</sub>
- D omega<sub>1</sub> = omega<sub>2</sub>
Correct answer: B. omega<sub>1</sub>/f<sub>1</sub> + omega<sub>2</sub>/f<sub>2</sub> = 0
Explanation: Achromatic doublet condition: omega<sub>1</sub>/f<sub>1</sub> + omega<sub>2</sub>/f<sub>2</sub> = 0, where omega is the dispersive power of each glass material.
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.