Physics · Refraction of light through a prism, microscope and astronomical telescope (reflecting and refracting) and their magnifying powers

Two convex lenses have focal lengths 10 and If a telescope has to be made by usi

Two convex lenses have focal lengths 10 \( \mathrm{cm} \) and \( 40 \mathrm{cm} . \) If a telescope has to be made by using these two lenses 1. The distance between the lenses should be \( 50 \mathrm{cm} \) 2. The distance between the lenses should be \( 30 \mathrm{cm} \) 3. The magnifying power of this telescope will be 5 4. An inverted image will be produced in this telescope Which two of the give are correct?

  • A. 1 and 4
  • B. 2 and 4
  • C. 1 and 3
  • D. 3 and 4

Step-by-step solution

For an astronomical telescope with objective focal length 40 cm and eyepiece focal length 10 cm, the distance between lenses for normal adjustment is 40 cm + 10 cm = 50 cm, so statement 1 is correct. The magnifying power is 40/10 = 4, not 5, so statement 3 is incorrect. The image formed is inverted, so statement 4 is correct. Thus, correct statements are 1 and 4.
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