A convex lens of power +4 D is brought in contact with a

power 4dTo find the focal length of the combination of two thin lenses in contact, we can follow these steps: Step 1: Identify the Powers of the Lenses We have two lenses: - Lens 1 has a power ( P1 = +4Anyway coming to your question the requirement of +- 4D for a job means that the eyesht of an applicant should not exceed these values that is +4D and -4D and in other