Question
Two lens of power (+ 4 D) and (- 6 D) are placed in contact with each other. What will be their combined focal length in cm?
Asked in RRB Technician Grade III · 2026
Lens · Physics
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Myopia is corrected with a concave lens; hypermetropia uses a convex lens.
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Questions Asked from LASER & Optical Fibre in Previous Exams
See how often LASER & Optical Fibre has appeared in previous-year questions across major government exams.
9UPSC Questions Asked in These Years:2010, 2011, 2012, 2013, 2019, 2021, 2022, 2023, 2024
9SSC Questions Asked in These Years:2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025
7Railways Questions Asked in These Years:2016, 2018, 2021, 2022, 2024, 2025, 2026
15State PSC Questions Asked in These Years:2002, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025
LASER & Optical Fibre has appeared in 40 previous-year exam questions, most frequently in State PSC, UPSC and SSC.
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