Q36. A compound microscope has objective focal length 2 cm and eyepiece focal length 5 cm. Tube length increases from 27 cm to 31 cm; the object is readjusted to keep the final image at infinity. Total angular magnification magnitude:
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Question

Q36. A compound microscope has objective focal length 2 cm and eyepiece focal length 5 cm. Tube length increases from 27 cm to 31 cm; the object is readjusted to keep the final image at infinity. Total angular magnification magnitude:

Options

G1 Physics · Accepted Answer

GIVEN: Compound microscope fₒ = 2 cm, fₑ = 5 cm, D = 25 cm. Tube length changes 27 cm → 31 cm; final image remains at ∞. Step 1: Eyepiece angular magnification mₑ = D/fₑ = 25/5 = 5 (unchanged). Step 2: Initially vₒ₁ = 27 − 5 = 22 cm; |mₒ₁| = 22/2 − 1 = 10 ⇒ |M₁| = 10 × 5 = 50. Step 3: Finally vₒ₂ = 31 − 5 = 26 cm; |mₒ₂| = 26/2 − 1 = 12 ⇒ |M₂| = 12 × 5 = 60. Step 4: Increase in magnitude = |M₂| − |M₁| = 60 − 50 = 10. FINAL ANSWER: Increases by 10. Option B.