Lenses and ray diagrams Quiz
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5 questions, one answer each
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1. A lens has a focal length of 0.20 m. What is its power?
- A. 0.20 D
- B. 5.0 D
- C. 2.0 D
- D. 20 D
2. A converging lens of power +6.0 D is placed in contact with a diverging lens of power −2.5 D. What is the power of the combination?
- A. +3.5 D
- B. −3.5 D
- C. +8.5 D
- D. +15 D
3. Which ray from the top of an object passes through a thin lens without being deviated?
- A. The ray parallel to the axis
- B. The ray through the optical centre
- C. The ray through the principal focus
- D. None of them
4. An object is placed 0.10 m from a converging lens of focal length 0.15 m. The image is
- A. real, inverted and diminished
- B. real, inverted and magnified
- C. virtual, upright and magnified
- D. virtual, upright and diminished
5. Which statement about a diverging lens is correct?
- A. It forms real images of real objects
- B. It has a positive power
- C. It can only form virtual images of real objects
- D. It brings parallel rays to a real focus